Fixing Git Bash Warp Proc Lock Error | Generated by AI
Question: How to fix the Cygwin/MSYS2 get_proc_lock / sync_proc_subproc error when using Git Bash as a terminal profile in Warp on Windows?
Answer:
The error is a classic Cygwin fork/proc locking issue:
[sig] bash 10696! get_proc_lock: Couldn't acquire sync_proc_subproc for(4,0), last 2, Win32 error 0
[sig] bash 10696! proc_subproc: couldn't get proc lock. what 4, val 0
This happens because Warp injects its own PTY/shell hooks that conflict with Cygwin’s process synchronization primitives. Git Bash is MSYS2/Cygwin-based, so it’s sensitive to how the parent process sets up the environment.
Fix options, in order of effectiveness:
1. Launch Git Bash with --login -i flags in Warp’s profile
In Warp → Settings → Features → Terminal Profiles, set the shell command to:
C:\Program Files\Git\bin\bash.exe --login -i
The --login flag ensures .bash_profile is sourced properly and Cygwin initializes its runtime correctly before Warp’s hooks fire.
2. Disable Warp’s shell integration for Git Bash
Warp’s shell integration (for prompt detection, command blocks, etc.) injects code that forks subprocesses — exactly what triggers this. In Warp settings, disable shell integration specifically for Git Bash, or add to your ~/.bashrc:
unset WARP_IS_LOCAL_SHELL_SESSION
3. Set MSYS env var to suppress fork warnings
Add to your Git Bash .bashrc or set in Warp’s profile environment variables:
MSYS=winsymlinks:nativestrict
MSYS2_ARG_CONV_EXCL="*"
More directly, the fork error is sometimes suppressed by:
MSYS=disable_pcon
4. Use Git Bash via mintty wrapper instead of bare bash.exe
C:\Program Files\Git\git-bash.exe
But this opens a separate window — not ideal for Warp embedding.
5. Switch to WSL2 as your Warp profile instead
Honestly the cleanest fix. Git Bash on Windows is a compatibility shim. If you’re doing serious dev work (which you are), WSL2 Ubuntu in Warp gives you a real Linux environment without the Cygwin proc-lock nonsense. Warp’s shell integration works natively with WSL2 bash/zsh.
Root cause in one sentence: Warp forks child processes to implement its command detection, and Cygwin’s sync_proc_subproc mutex times out or fails when the parent process (Warp) doesn’t conform to Cygwin’s expected process tree — Win32 error 0 means the lock object wasn’t found, not a permission error.