bash.exe.stackdump files left behind in working directories on Windows (Git Bash / MSYS2)

Description

Claude Code leaves bash.exe.stackdump files in the working directory after sessions. These files are MSYS2 crash dump artifacts generated when the bash process terminates abnormally. They accumulate across every directory where Claude Code has been active, cluttering repositories and requiring manual cleanup.

Reproduction

1. Open Claude Code on Windows with Git Bash as the shell
2. Work normally in any project directory (run commands, use the Bash tool, etc.)
3. After the session (or even during), check the working directory
4. A bash.exe.stackdump file is present

This happens consistently across sessions and directories. No specific command or interaction triggers it — it appears to be caused by how Claude Code spawns and terminates bash subprocesses.

Evidence

On my machine, I found 6 stackdump files across different repositories, all with identical content and size (1196 bytes). They span multiple days, confirming this is a persistent recurring issue, not a one-off crash:

-rw-r--r-- 1196 Mar 23 14:43 project-A/bash.exe.stackdump
-rw-r--r-- 1196 Mar 23 14:01 project-B/bash.exe.stackdump
-rw-r--r-- 1196 Mar 23 12:23 project-C/bash.exe.stackdump
-rw-r--r-- 1196 Mar 23 11:13 project-D/bash.exe.stackdump
-rw-r--r-- 1196 Mar 23 10:59 project-E/bash.exe.stackdump
-rw-r--r-- 1196 Mar 20 17:16 project-F/bash.exe.stackdump

Stack trace content

Every file has the same crash signature — a fault inside msys-2.0.dll:

Stack trace:
Frame         Function      Args
0007FFFFB740  00021005FE8E (000210285F68, 00021026AB6E, 0007FFFFB740, 0007FFFFA640) msys-2.0.dll+0x1FE8E
0007FFFFB740  0002100467F9 (000000000000, 000000000000, 000000000000, 0007FFFFBA18) msys-2.0.dll+0x67F9
0007FFFFB740  000210046832 (000210286019, 0007FFFFB5F8, 0007FFFFB740, 000000000000) msys-2.0.dll+0x6832
0007FFFFB740  000210068CF6 (000000000000, 000000000000, 000000000000, 000000000000) msys-2.0.dll+0x28CF6
0007FFFFB740  000210068E24 (0007FFFFB750, 000000000000, 000000000000, 000000000000) msys-2.0.dll+0x28E24
0007FFFFBA20  00021006A225 (0007FFFFB750, 000000000000, 000000000000, 000000000000) msys-2.0.dll+0x2A225
End of stack trace

Expected behavior

Claude Code should either:

1. Clean up bash.exe.stackdump files after they are generated, or
2. Prevent the crash that generates them (e.g., graceful subprocess termination), or
3. Configure the MSYS2 environment to suppress stackdump generation (via set MSYS=error_start or export CYGWIN=nodumps)

Environment

• OS: Windows 11 Pro (10.0.26200)
• Shell: Git Bash (MINGW64)
• Bash version: GNU bash 5.2.26(1)-release (x86_64-pc-msys)
• MSYS2 runtime: msys-2.0.dll (3.4.10-87d57229, 2024-02-14)
• Claude Code version: 2.1.81

Additional context

• The crash occurs inside msys-2.0.dll, not in bash itself, suggesting the MSYS2 runtime is receiving an unexpected signal during subprocess teardown.
• All stackdump files are identical (same size, same trace), pointing to a single reproducible crash path rather than random failures.
• The files are not .gitignored by default, so they can accidentally be committed if users aren't careful.
• Setting MSYS=error_start: (empty value) as an environment variable before launching bash suppresses stackdump file creation entirely. This could be a quick fix on Claude Code's side when spawning bash processes on Windows.