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client: suppress duplicate abort errors during StreamableHTTP close - #1817

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client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
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windro-xdd:fix/streamable-http-close-no-duplicate-onerror

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@windro-xddwindro-xdd commented Mar 29, 2026

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Summary

  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior

Why

Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.

Validation

  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint

Closes#868

@windro-xdd
windro-xdd requested a review from a team as a code ownerMarch 29, 2026 15:41
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Latest commit: d322291

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

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@felixweinberger

felixweinberger commented Mar 31, 2026

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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.

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When executing client.close(), onerror will be executed twice (Streamable HTTP)

2 participants

@windro-xdd@felixweinberger
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client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
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client: suppress duplicate abort errors during StreamableHTTP close - #1817
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windro-xdd wants to merge 1 commit into
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client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
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windro-xdd:fix/streamable-http-close-no-duplicate-onerror
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@windro-xdd
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Mar 29, 2026

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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
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as a code ownerMarch 29, 2026 15:41
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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
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commit: d322291
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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


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client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
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windro-xdd wants to merge 1 commit into
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client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
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@windro-xdd
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commented
Mar 29, 2026

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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
windro-xdd
requested a review
from a team
as a code ownerMarch 29, 2026 15:41
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Mar 29, 2026

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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1817

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1817

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1817

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1817

commit: d322291
@felixweinberger
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Mar 31, 2026

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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


2 participants

@windro-xdd@felixweinberger

, 'i');
if (__m === '*' || __re.test(location.href)) {
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
Closed
windro-xdd wants to merge 1 commit into
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windro-xdd:fix/streamable-http-close-no-duplicate-onerror
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client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
windro-xdd
requested a review
from a team
as a code ownerMarch 29, 2026 15:41
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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1817

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1817

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
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@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1817

commit: d322291
@felixweinberger
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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


2 participants

@windro-xdd@felixweinberger

, 'i');
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var __re = new RegExp('^' + "youtube\\.com" + '
client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
Closed
windro-xdd wants to merge 1 commit into
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client: suppress duplicate abort errors during StreamableHTTP close#1817
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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
windro-xdd
requested a review
from a team
as a code ownerMarch 29, 2026 15:41
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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1817

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1817

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1817

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1817

commit: d322291
@felixweinberger
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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


2 participants

@windro-xdd@felixweinberger

, 'i');
if (__m === '*' || __re.test(location.href)) {
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
Closed
windro-xdd wants to merge 1 commit into
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windro-xdd:fix/streamable-http-close-no-duplicate-onerror
Closed
client: suppress duplicate abort errors during StreamableHTTP close#1817
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windro-xdd:fix/streamable-http-close-no-duplicate-onerror
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@windro-xdd
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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


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client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
Closed
windro-xdd wants to merge 1 commit into
modelcontextprotocol:mainfrom 
windro-xdd:fix/streamable-http-close-no-duplicate-onerror
Closed
client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
modelcontextprotocol:mainfrom 
windro-xdd:fix/streamable-http-close-no-duplicate-onerror
Conversation
@windro-xdd
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Mar 29, 2026

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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
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from a team
as a code ownerMarch 29, 2026 15:41
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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1817

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1817

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1817

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1817

commit: d322291
@felixweinberger
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Mar 31, 2026

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Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


2 participants

@windro-xdd@felixweinberger

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client: suppress duplicate abort errors during StreamableHTTP close by windro-xdd · Pull Request #1817 · modelcontextprotocol/typescript-sdk · GitHub
Skip to content
client: suppress duplicate abort errors during StreamableHTTP close - #1817
Closed
windro-xdd wants to merge 1 commit into
modelcontextprotocol:mainfrom 
windro-xdd:fix/streamable-http-close-no-duplicate-onerror
Closed
client: suppress duplicate abort errors during StreamableHTTP close#1817
windro-xdd wants to merge 1 commit into
modelcontextprotocol:mainfrom 
windro-xdd:fix/streamable-http-close-no-duplicate-onerror
Conversation
@windro-xdd
@windro-xddwindro-xdd
commented
Mar 29, 2026

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Summary
  • add a close-state guard in StreamableHTTPClientTransport to suppress abort-driven onerror emissions while shutdown is in progress
  • keep normal error behavior unchanged when not closing
  • route internal error reporting through a single _emitError helper to avoid duplicate callback paths
  • add regression tests for client.close() abort behavior
Why
Issue #868 reports duplicate onerror callbacks when closing a Streamable HTTP client. During shutdown, in-flight requests can reject with AbortError, and those errors should not be surfaced as user-facing failures after an intentional close.
Validation
  • pnpm --filter @modelcontextprotocol/client test -- test/client/streamableHttp.test.ts
  • pnpm --filter @modelcontextprotocol/client typecheck
  • pnpm --filter @modelcontextprotocol/client lint
Closes#868
@windro-xdd
windro-xdd
requested a review
from a team
as a code ownerMarch 29, 2026 15:41
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Mar 29, 2026

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⚠️ No Changeset found
Latest commit: d322291
Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.
This PR includes no changesets
When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types
Click here to learn what changesets are, and how to add one.
Click here if you're a maintainer who wants to add a changeset to this PR
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@modelcontextprotocol/client
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/client@1817

@modelcontextprotocol/server
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/server@1817

@modelcontextprotocol/express
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/express@1817

@modelcontextprotocol/hono
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/hono@1817

@modelcontextprotocol/node
npm i https://pkg.pr.new/modelcontextprotocol/typescript-sdk/@modelcontextprotocol/node@1817

commit: d322291
@felixweinberger
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Mar 31, 2026

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Contributor
Thanks for picking this up. Taking a different direction here: #880 identified the root cause (_startOrAuthSse's catch at :296 fires onerror then throws, and all three callers already .catch(onerror), so every failure double-fires, not just during close). Opening a fresh PR based on that approach.
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When executing client.close(), onerror will be executed twice (Streamable HTTP)


2 participants

@windro-xdd@felixweinberger