Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691

Merged
lpcox merged 3 commits into
mainfrom
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged

Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom
copilot/fix-browser-navigation-error

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CopilotAI commented Feb 5, 2026•
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Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.

Changes

Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:

  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)

Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.

PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'

Standard pattern for Playwright in Docker per official docs.

Original prompt

This section details on the original issue you should resolve

<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>
<issue_description>## MCP Server Stress Test - Non-Authentication Failure

The nightly stress test detected 1 server with a non-authentication failure.

Test Summary

  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1

Failed Server

1. playwright - Browser Navigation Error

Container: mcr.microsoft.com/playwright:v1.49.1-noble

Issue Type: Security Policy / Browser Configuration

Status:⚠️ Partial Success (browser launches but navigation blocked)

Error:

Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:
The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:

  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings

The MCP server itself is functional; this is a browser configuration issue.

Suggested Investigation:

  • Review browser launch options in the Playwright server configuration
  • Disable browser extensions or security add-ons
  • Use headless mode without UI extensions
  • Check for CSP headers or security policies in the browser profile
  • Verify browser args don't include overly restrictive security flags
  • Test with different URLs to isolate the issue

Test Configuration

The test used the following setup:

  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1

Gateway Performance

✅ No gateway-level issues detected:

  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts

Next Steps

  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify

Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515

Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md

AI generated by Nightly MCP Server Stress Test

<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>

Comments on the Issue (you are @copilot in this section)

Custom agent used: agentic-workflows
GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

CopilotAIand others added 2 commits February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI changed the title [WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI requested a review from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox marked this pull request as ready for review February 5, 2026 03:23
CopilotAI review requested due to automatic review settings February 5, 2026 03:23
@lpcox
lpcox merged commit 7d92126 into mainFeb 5, 2026
4 checks passed
@lpcox
lpcox deleted the copilot/fix-browser-navigation-error branch February 5, 2026 03:24
CopilotAI reviewed Feb 5, 2026
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Pull request overview

This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.

Changes:

  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

@coderabbitaicoderabbitaiBot mentioned this pull request Jul 28, 2026
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[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy

3 participants

@lpcox
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

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Contributor
Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
CopilotAI
reviewed
Feb 5, 2026
View reviewed changes
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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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Successfully merging this pull request may close these issues.

[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

Loading

Copy link


Copy Markdown

Contributor
Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
CopilotAI
reviewed
Feb 5, 2026
View reviewed changes
CopilotAI
left a comment


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Choose a reason for hiding this comment

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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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Successfully merging this pull request may close these issues.

[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

Loading

Copy link


Copy Markdown

Contributor
Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

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Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
CopilotAI
reviewed
Feb 5, 2026
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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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Successfully merging this pull request may close these issues.

[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

Loading

Copy link


Copy Markdown

Contributor
Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
CopilotAI
reviewed
Feb 5, 2026
View reviewed changes
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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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Successfully merging this pull request may close these issues.

[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
Merged
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Feb 5, 2026
Merged
Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
mainfrom 
copilot/fix-browser-navigation-error
Conversation
CopilotAI
commented
Feb 5, 2026•

edited

Loading

Copy link


Copy Markdown

Contributor
Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
Custom agent used: agentic-workflows

GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing
✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.
CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
CopilotAI
changed the title
[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
CopilotAI
requested a review
from lpcoxFebruary 5, 2026 03:20
@lpcox
lpcox
marked this pull request as ready for review
February 5, 2026 03:23
CopilotAI
review requested due to automatic review settings
February 5, 2026 03:23
@lpcox
lpcox
merged commit 7d92126
into
mainFeb 5, 2026

4 checks passed

@lpcox
lpcox
deleted the

copilot/fix-browser-navigation-error

branch
February 5, 2026 03:24
CopilotAI
reviewed
Feb 5, 2026
View reviewed changes
CopilotAI
left a comment


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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
@coderabbitaicoderabbitaiBot
mentioned this pull request
Jul 28, 2026
 Merged

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Applies to this pull request for everyone.Learn more about Copilot code review.
Copilot left review comments
@lpcoxlpcoxAwaiting requested review from lpcox

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Successfully merging this pull request may close these issues.

[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


3 participants

@lpcox

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags - #691
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lpcox merged 3 commits into
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copilot/fix-browser-navigation-error
Feb 5, 2026
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Fix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flags#691
lpcox merged 3 commits into
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copilot/fix-browser-navigation-error
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Playwright MCP server was failing navigation with ERR_BLOCKED_BY_CLIENT despite container launching successfully. Chromium's sandbox requirements aren't met in Docker containers without explicit bypass flags.
Changes
Added Docker-specific Chromium launch flags to PLAYWRIGHT_LAUNCH_OPTIONS:
  • --no-sandbox - bypass Linux sandbox restrictions
  • --disable-setuid-sandbox - additional sandbox bypass
  • --disable-gpu - disable GPU acceleration (unavailable in headless containers)
Enhanced security warning to explicitly note these flags disable critical browser protections and should only be used in controlled CI environments.
PLAYWRIGHT_LAUNCH_OPTIONS: '{"args": ["--no-sandbox", "--disable-setuid-sandbox", "--disable-gpu", "--disable-blink-features=AutomationControlled", "--disable-web-security", "--disable-features=IsolateOrigins,site-per-process"]}'
Standard pattern for Playwright in Docker per official docs.
Original prompt
This section details on the original issue you should resolve
<issue_title>[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy</issue_title>

<issue_description>## MCP Server Stress Test - Non-Authentication Failure
The nightly stress test detected 1 server with a non-authentication failure.
Test Summary
  • Test Session: stress-test-20260205-030515
  • Test Date: 2026-02-05T03:05:15Z
  • Total Non-Auth Failures: 1
Failed Server
1. playwright - Browser Navigation Error
Container: mcr.microsoft.com/playwright:v1.49.1-noble
Issue Type: Security Policy / Browser Configuration
Status:⚠️ Partial Success (browser launches but navigation blocked)
Error:
Error: page.goto: net::ERR_BLOCKED_BY_CLIENT at (example.com/redacted)
Call log:
- navigating to "(example.com/redacted), waiting until "domcontentloaded"

Analysis:

The Playwright MCP server and browser launch successfully, indicating the container and MCP protocol communication are working correctly. However, navigation attempts are blocked by a client-side security policy (ERR_BLOCKED_BY_CLIENT). This error typically occurs when:
  • An ad blocker or security extension is active in the browser profile
  • Content Security Policy (CSP) blocks the navigation
  • Browser launch args include restrictive security settings
The MCP server itself is functional; this is a browser configuration issue.
Suggested Investigation:
  •  Review browser launch options in the Playwright server configuration
  •  Disable browser extensions or security add-ons
  •  Use headless mode without UI extensions
  •  Check for CSP headers or security policies in the browser profile
  •  Verify browser args don't include overly restrictive security flags
  •  Test with different URLs to isolate the issue
Test Configuration
The test used the following setup:
  • MCP Gateway: Pre-configured via workflow infrastructure
  • Test Method: Sequential server testing with simple tool invocations
  • Playwright Browser: Containerized Playwright v1.49.1
Gateway Performance
✅ No gateway-level issues detected:
  • MCP protocol communication working correctly
  • Container launched successfully
  • Error responses properly formatted
  • No crashes or timeouts
Next Steps
  1. Investigate browser launch configuration
  2. Apply fixes to browser settings
  3. Re-run stress test to verify
Generated by Nightly MCP Stress Test
Test Session: stress-test-20260205-030515
Full Test Results: See workflow run artifacts at /tmp/mcp-stress-results/test_report.md
AI generated by Nightly MCP Server Stress Test
<agent_instructions>Only update the .md file, not the .lock.yml file. </agent_instructions>
Comments on the Issue (you are @copilot in this section)
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CopilotAIand others
added 2 commits
February 5, 2026 03:18
@lpcox
Add Docker-specific Chromium flags to fix ERR_BLOCKED_BY_CLIENT
55e6888
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
@lpcox
Enhance security warning for Docker-specific browser flags
7ac63c2
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
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[WIP] Fix Playwright MCP server browser navigation error due to security policyFix Playwright ERR_BLOCKED_BY_CLIENT in Docker by adding sandbox bypass flagsFeb 5, 2026
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marked this pull request as ready for review
February 5, 2026 03:23
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February 5, 2026 03:23
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Pull request overview
This PR fixes the Playwright MCP server's browser navigation failure in Docker environments by adding required Chromium sandbox bypass flags and enhanced security documentation.
Changes:
  • Added Docker-specific Chromium launch flags (--no-sandbox, --disable-setuid-sandbox, --disable-gpu) to PLAYWRIGHT_LAUNCH_OPTIONS
  • Enhanced security warning with explicit multi-line documentation about disabled security features
  • Added reference to official Playwright Docker documentation
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Jul 28, 2026
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[mcp-stress-test] Playwright MCP server browser navigation blocked by security policy


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