macOS segfault: copilot crashes with EXC_BAD_ACCESS (SIGSEGV)

[chokevin]

Summary

copilot crashes with a segmentation fault on macOS when invoked from terminal.

Repro

1. Launch terminal (cmux in my case).
2. Run copilot.
3. Process exits with segmentation fault ([1] 94078 segmentation fault copilot).

Expected

CLI starts normally.

Actual

CLI crashes immediately with SIGSEGV.

Crash report

• File: ~/Library/Logs/DiagnosticReports/copilot-2026-04-23-153812.ips
• Incident ID: 7CE3EF49-27EA-4633-A900-D701E388DE69
• Exception: EXC_BAD_ACCESS / SIGSEGV
• Subtype: KERN_INVALID_ADDRESS at 0x000000000000000b
• Faulting thread: V8Worker
• Parent PID recorded in crash report: 94078

Environment

• macOS: 26.4.1 (25E253)
• Hardware: Apple Silicon (Mac15,3 from crash report)
• Terminal host process in report: cmux

copilot version

GitHub Copilot CLI 1.0.35-6.
Run 'copilot update' to check for updates.

Additional notes

• Crash report includes symbols pointing into V8 worker/concurrent marking paths.
• I can attach the full .ips report if needed.

Environment snapshot

  ProductName:		macOS
  ProductVersion:		26.4.1
  BuildVersion:		25E253
Darwin Kevins-MacBook-Pro.local 25.4.0 Darwin Kernel Version 25.4.0: Thu Mar 19 19:32:59 PDT 2026; root:xnu-12377.101.15~1/RELEASE_ARM64_T8122 arm64
Captured at: 2026-04-23 15:42:58 -0700

[chokevin]

Adding a bit more detail from the crash report for triage:

Parsed crash metadata

• incident: 7CE3EF49-27EA-4633-A900-D701E388DE69
• captureTime: 2026-04-23 15:38:03.5644 -0700
• proc pid/parentPid: 77579 / 94078
• exception: EXC_BAD_ACCESS SIGSEGV (KERN_INVALID_ADDRESS at 0x000000000000000b)
• faulting thread index/name: 3 / V8Worker

Faulting thread (top frames)

v8::internal::ConcurrentMarking::RunMajor(v8::JobDelegate*, v8::base::EnumSet<v8::internal::CodeFlushMode, int>, unsigned int, bool) +988
v8::internal::ConcurrentMarking::JobTaskMajor::Run(v8::JobDelegate*) +448
v8::platform::DefaultJobWorker::Run() +216
node::(anonymous namespace)::PlatformWorkerThread(void*) +564
_pthread_start +136
thread_start +8

Main thread around event loop (top frames)

Builtins_StringEqual +228
Builtins_FindOrderedHashMapEntry +1200
imageIndex=3 offset=4944145388
imageIndex=3 offset=4942170488
imageIndex=3 offset=4932181196
imageIndex=3 offset=4949886164
imageIndex=3 offset=4932180164
Builtins_ArrayReduce +972

Loaded native Node modules in process

• keytar.node (/Users/USER/*/keytar.node)
• pty.node (/Users/USER/*/pty.node)

If helpful, I can provide the full .ips contents verbatim in a follow-up.