[BUG] Claude Code crashes with SIGABRT during shutdown due to MCP server termination failure

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I have searched existing issues and this hasn't been reported yet
This is a single bug report (please file separate reports for different bugs)
I am using the latest version of Claude Code

What's Wrong?

Claude Code crashes with SIGABRT during shutdown when attempting to terminate MCP (Model Context Protocol) servers. The crash occurs during the cleanup phase when the application cannot properly shut down connected MCP servers, leading to a Node.js assertion failure during stdio cleanup.

What Should Happen?

Claude Code should exit cleanly after properly terminating all MCP server processes and cleaning up resources.

Error Messages/Logs

SIGINT failed, sending SIGTERM to MCP server process
  Error sending SIGTERM:
  SIGTERM failed, sending SIGKILL to MCP server process
  Error sending SIGKILL:
  Error terminating process:
  Error closing client:
  Cleanup timeout reached, stopping process monitoring

  Process terminates with SIGABRT and generates core dump (261MB core file).

Steps to Reproduce

Start Claude Code with MCP servers configured
Use Claude Code normally (any operations)
Exit Claude Code (Ctrl+C, quit command, or other exit method)
Application crashes during shutdown process with core dump

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

No response

Claude Code Version

1.0.113

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

Stack trace analysis:

Crash point: node::ResetStdio() during exit cleanup
Signal: SIGABRT (assertion failure)
Root cause: MCP servers failed to terminate (SIGINT → SIGTERM → SIGKILL all failed)
Node.js cleanup assertion failed when trying to reset stdio during exit

Technical details:

Executable: /usr/bin/node (Claude Code)
Core dump shows uncaught exception during shutdown sequence
MCP server termination timeout reached before clean exit

Facing the same error

The same error

Claude Code Crash Report

Summary

Claude Code crashed with SIGABRT during error cleanup. This appears to be a Node.js core bug where node::ResetStdio() fires an assertion during legitimate error scenarios.

Environment

Claude Code CLI: @anthropic-ai/claude-code
Node.js: v20.19.5
Platform: Linux x86_64
Signal: SIGABRT (Aborted)

Root Cause

1. Write error (EIO) → stream closed during active output
2. Uncaught exception handler triggered exit
3. Exit cleanup called node::ResetStdio()
4. Assertion failed → SIGABRT

Stack Trace (gdb analysis)

Thread 1 (crashed):
#5  node::Assert(node::AssertionInfo const&)
#6  node::ResetStdio() [clone .part.0]        ← ASSERTION FAILED
#7  node::TrapWebAssemblyOrContinue(...)
...
#16 __run_exit_handlers()                      ← During exit cleanup
#17 __GI_exit()
#18 node::DefaultProcessExitHandlerInternal()
#19 node::Environment::Exit()
#20 node::errors::TriggerUncaughtException()   ← Original error handler
...
#30 node::ReportWritesToJSStreamListener::OnStreamAfterReqFinished()
#31 node::WriteWrap::OnDone(int)               ← Original write error (EIO)

The assertion fired twice - once during exit, then again while trying to dump the first assertion failure.

Reproduction

Terminal/stream closed while Claude Code was streaming output
High volume of data being written at time of disconnect
Race condition between output generation and stream closure

Expected Behavior

Node.js should handle stream closure gracefully during exit, not trigger assertions. Write errors (EIO, EPIPE) are normal when terminals disconnect.

Actual Behavior

Process aborted with SIGABRT and 317MB core dump.

Suggested Fix

Add defensive checks before stream writes:

if (stream.writable && !stream.destroyed) {
  stream.write(data);
}

This prevents the EIO error that triggers the problematic exit path.

Note

This may be more appropriate as a Node.js issue rather than Claude Code, since the assertion is in Node.js core code. However, Claude Code could work around it with the defensive checks above.

We’ve reproduced this with setting_sources enabled; see detailed analysis in #1935. Also relates to cancel scope bug in #8999

This issue has been inactive for 30 days. If the issue is still occurring, please comment to let us know. Otherwise, this issue will be automatically closed in 30 days for housekeeping purposes.

Handle shutdown signals gracefully in MCP server (#4227)

2026-01-22 15:21:14.434 [info] From claude: ============================================================
Bun v1.3.6 (d530ed99) Linux x64 (baseline)
Linux Kernel v6.1.25 | glibc v2.35
CPU: sse42 popcnt
Args: "/home/ashu/.vscode/extensions/anthropic.claude-code-2.1.15-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose" "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "defa"...
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) fetch(47) jsc no_avx2 no_avx spawn(16) standalone_executable
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "node:domain" "node:events" "node:fs" "node:fs/promises" "node:http" "node:https" "node:module" "node:net" "node:os" "node:path" "node:path/posix" "node:path/win32" "node:perf_hooks" "node:process" "node:querystring" "node:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util
2026-01-22 15:21:14.703 [info] Closing Claude on channel: hm0ylw07d2j
2026-01-22 15:21:14.706 [error] Error from Claude (on channel hm0ylw07d2j): Error: Claude Code process terminated by signal SIGABRT
2026-01-22 15:21:20.094 [info] Received message from webview: {"type":"request","requestId":"uhqdcl8omc","request":{"type":"open_output_panel"}}

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.

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[BUG] Claude Code crashes with SIGABRT during shutdown due to MCP server termination failure #7718

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What's Wrong?

What Should Happen?

Error Messages/Logs

Steps to Reproduce

Claude Model

Is this a regression?

Last Working Version

Claude Code Version

Platform

Operating System

Terminal/Shell

Additional Information

Claude Code Crash Report

Summary

Environment

Root Cause

Stack Trace (gdb analysis)

Reproduction

Expected Behavior

Actual Behavior

Suggested Fix

Note

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[BUG] Claude Code crashes with SIGABRT during shutdown due to MCP server termination failure #7718

Description

Preflight Checklist

What's Wrong?

What Should Happen?

Error Messages/Logs

Steps to Reproduce

Claude Model

Is this a regression?

Last Working Version

Claude Code Version

Platform

Operating System

Terminal/Shell

Additional Information

Activity

navvye commented on Oct 13, 2025

kasnet commented on Oct 14, 2025

jgspratt commented on Oct 15, 2025

Claude Code Crash Report

Summary

Environment

Root Cause

Stack Trace (gdb analysis)

Reproduction

Expected Behavior

Actual Behavior

Suggested Fix

Note

MarkDeVerno commented on Dec 3, 2025

github-actions commented on Jan 4, 2026

loneranger98 commented on Jan 22, 2026

github-actions commented on Feb 28, 2026

github-actions commented on Mar 7, 2026

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