Bun runtime crash: panic(main thread): switch on corrupt value on Windows 10

[jiaoshi888]

Bug Description

Claude Code crashes with a Bun runtime panic after extended usage on Windows 10.

Error Message

panic(main thread): switch on corrupt value
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Environment

• OS: Windows 10 x64 (win10_ni)
• Bun version: v1.3.10 (1423d3c8)
• CPU: sse4.2 avx avx2
• Claude Code path: C:\Users\Administrator\.local\bin\claude.exe

Runtime Stats at Crash

• Elapsed: 953490ms (~15 minutes)
• User: 37531ms | Sys: 5234ms
• RSS: 0.98GB | Peak: 1.07GB | Commit: 1.40GB
• Page Faults: 1295216 | Machine: 68.53GB

Bun Crash Report

Bun provided the following crash report URL:
https://bun.report/1.3.10/e_l1423d3cmgkgEuhogD0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLo35FCSntdll.dllipmTA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

Steps to Reproduce

1. Run Claude Code on Windows 10
2. Use it for an extended session (~15+ minutes)
3. Claude Code crashes with the above panic

Expected Behavior

Claude Code should not crash with a Bun runtime panic.

Additional Notes

The crash occurs in the Bun runtime that bundles Claude Code. This may be related to memory corruption or an unexpected code path after prolonged usage.

[github-actions]

Found 2 possible duplicate issues:

1. Recurring Bun crash on Windows: panic(main thread): switch on corrupt value #26590
2. [BUG] [Windows] Bun panic "switch on corrupt value" crashes during Bash tool execution (v2.1.45 / Bun 1.3.10-canary.63) #26531

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[MartinWickman]

Happened on 2.1.47

Bun Canary v1.3.10-canary.63 (1979c945) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2
Args: "claude"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) abort_signal(28) fetch(103) jsc spawn(304) standalone_executable process_dlopen yaml_parse(28)
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "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:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "node:worker_threads" "undici" "ws" "node:http2"
Elapsed: 301623ms | User: 11843ms | Sys: 3296ms
RSS: 0.64GB | Peak: 0.75GB | Commit: 0.88GB | Faults: 600481 | Machine: 0.14TB

panic(main thread): switch on corrupt value
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

[gophren]

Experiencing the same panic on Windows 11. Two instances, same Bun version:

Crash 1 – after ~1h53m session (Elapsed: 6814950ms)
https://bun.report/1.3.10/e_11423d3cmgkgEuhogC0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLut0LCSntdll.dll4zijBA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

Crash 2 – after only ~4 seconds using claude -c (Elapsed: 4110ms)
https://bun.report/1.3.10/e_11423d3cmgkgEugogC0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLut0LCSntdll.dll4zijBA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

Environment: Windows 11 x64 | CPU: sse42 avx avx2

Possible RAM misread: Physical RAM is 32.0 GB (confirmed via Task Manager), but Bun reported Machine: 34.07GB in both crash logs. This ~2GB discrepancy may indicate Bun is misreading total physical memory on this system (2x SODIMM, 5600 MT/s). If Bun uses this value to size heap or GC thresholds, it could explain the switch on corrupt value panic.

Memory context at crash time: System was already at 61% memory usage (19.3/31.7 GB in use), with committed memory at 29.5/48.7 GB. The 4-second crash on claude -c rules out memory exhaustion over time as the sole cause — something in session resume may be triggering a corrupted state immediately.

[Boysiee]

im getting the same issue..
Bun v1.3.10 (1423d3c8) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2 avx512
Args: "claude"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) abort_signal(7) fetch(37) jsc spawn(73) standalone_executable process_dlopen(2) yaml_parse(61)
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "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:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "node:worker_threads" "undici" "ws"
Elapsed: 48486ms | User: 5625ms | Sys: 1765ms
RSS: 0.76GB | Peak: 0.86GB | Commit: 1.14GB | Faults: 355500 | Machine: 68.59GB

panic(main thread): switch on corrupt value
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

https://bun.report/1.3.10/e_11423d3cmgkgEuhogC0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLut0LCSntdll.dll4gijBA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

[Joe-TheBro]

Same issue here as well.

Bun v1.3.10 (1423d3c8) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2 avx512
Args: "claude" "--output-format" "stream-json" "--verbose" "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--mod"
2026-02-22 18:24:41.265 [info] From claude: ...
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) abort_signal(17) fetch(118) jsc spawn(29) standalone_executable process_dlopen
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "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:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "node:worker_threads" "undici" "ws" "node:http2"

2026-02-22 18:24:41.265 [info] From claude: Elapsed: 1653226ms | User: 3890ms | Sys: 2046ms
RSS: 0.74GB | Peak: 0.79GB | Commit: 1.12GB | Faults: 763343 | Machine: 0.13TB

panic(main thread): switch on corrupt value

2026-02-22 18:24:41.265 [info] From claude: oh no: Bun has crashed. This indicates a bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

2026-02-22 18:24:41.265 [info] From claude: https://bun.report/1.3.10/e_11423d3cmgEuhogC0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLut0LCSntdll.dll4zijBA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

[rythazhur]

Same here:

Bun v1.3.10 (1423d3c8) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2 avx512
Args: "claude" "--resume" "dafc98a5-1e2e-47de-a078-d7a786289e2e"
Features: Bun.stderr Bun.stdin(2) Bun.stdout(3) abort_signal(110) fetch(213) jsc spawn(132) standalone_executable process_dlopen(2) yaml_parse(30)
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "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:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "node:worker_threads" "undici" "ws"
Elapsed: 239606ms | User: 23000ms | Sys: 6015ms
RSS: 0.95GB | Peak: 1.19GB | Commit: 1.45GB | Faults: 1437384 | Machine: 0.14TB

panic(main thread): switch on corrupt value
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

https://bun.report/1.3.10/e_11423d3cmgkgEuhogC0w3jQk8vtbi+p4Vw7r0U23wN+o5gUmznlOqn4kOwkkqvDCYKERNEL32.DLLut0LCSntdll.dll4zijBA0eNorLs8sSc5QyM9TSM4vKiotKFEoS8wpTQUAa8EI/A

[Younesfdj]

same after using claude for ~1min

Error log:

============================================================
Bun v1.3.10 (1423d3c8) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2
Args: "claude"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) fetch(59) jsc spawn(13) standalone_executable process_dlopen(2)
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "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:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "node:worker_threads" "undici" "ws"
Elapsed: 202505ms | User: 23046ms | Sys: 8078ms
RSS: 10.59GB | Peak: 10.79GB | Commit: 33.82GB | Faults: 4552490 | Machine: 15.89GB

panic(thread 23768): Illegal instruction at address 0x7FF7BD7E35FB
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Error report and stack trace: https://bun.report/1.3.10/e_11423d3cmgEugogC2/6k2Coh7itC+kpjtC6l4/sCm/z/sCmxz/sCot5s3Bk16s3By21u2BmsvxvDCYKERNEL32.DLLut0LCSntdll.dll4gijBA3u//BrglnwiC

[ThatDragonOverThere]

7 Independent Reports of This Exact Panic

For anyone landing here: this "switch on corrupt value" panic has been reported independently in #26590, #26531, #27095, #27086, #28052, and #27847 — all Windows, all Bun v1.3.10. Community root cause analysis on #21875 points to an N-API race condition. That issue has had high-priority + oncall labels for 30+ days with no staff response.

If you're experiencing this, thumbs-up #21875 — that's where the memory dumps and WinDbg traces are.