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Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449

Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature

Description

@AmirL
AmirL
opened on Dec 9, 2025

Is there an existing issue for this?

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/nextjs

SDK Version

10.29.0

Framework Version

NextJs 15

Link to Sentry event

No response

Reproduction Example/SDK Setup

No response

Steps to Reproduce

The fetch instrumentation modifies network error messages by appending the hostname:

// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"

Expected Result

The Problem

Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:

consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);

When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:

  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path

Suggested Solutions

  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object

Actual Result

Additional Context

No response

Priority

React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.

Metadata

Metadata

Assignees

Labels

CoreFeature

Projects

Milestone

No milestone

Relationships

None yet

Development

No branches or pull requests

Issue actions

, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
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;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
Metadata
Metadata
Assignees
Labels
CoreFeature
Projects
Milestone
No milestone
Relationships
None yet
Development
No branches or pull requests
Issue actions

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Appending hostname to fetch error messages breaks is-network-error and p-retry packages · Issue #18449 · getsentry/sentry-javascript · GitHub
Skip to content
Appending hostname to fetch error messages breaks is-network-error and p-retry packages #18449
Closed
#18466
Closed
Appending hostname to fetch error messages breaks is-network-error and p-retry packages#18449
#18466
Assignees
JPeer264
Labels
CoreFeature
Description
@AmirL
AmirL
opened on Dec 9, 2025
Is there an existing issue for this?
How do you use Sentry?
Sentry Saas (sentry.io)
Which SDK are you using?
@sentry/nextjs
SDK Version
10.29.0
Framework Version
NextJs 15
Link to Sentry event
No response
Reproduction Example/SDK Setup
No response
Steps to Reproduce
The fetch instrumentation modifies network error messages by appending the hostname:
// packages/core/src/instrument/fetch.ts:106-123error.message=`${error.message} (${url.host})`;// "Failed to fetch" → "Failed to fetch (example.com)"
Expected Result
The Problem
Popular packages like is-network-error (2M+ downloads/week) and p-retry (6M+ downloads/week) rely on exact error message matching:
consterrorMessages=newSet(['Failed to fetch',// Exact match required'Load failed','NetworkError when attempting to fetch resource.',]);
When Sentry modifies the message to "Failed to fetch (example.com)", these packages no longer recognize it as a network error, causing:
  • p-retry stops retrying network failures
  • Legitimate transient errors fail permanently
  • Breaking change with no migration path
Suggested Solutions
  1. Add opt-out configuration: enhanceFetchErrors: false
  2. Add hostname as an error property instead of modifying the message
  3. Only modify the message in beforeSend, not the original error object
Actual Result
Additional Context
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