Bash tool fails with EINVAL on WSL commands in Windows 11

Environment

• OS: Windows 11
• Claude Code version: Latest (as of 2026-02-27)
• Shell: WSL2 (Ubuntu)

Description

Bash tool intermittently fails with EINVAL: invalid argument when attempting to execute WSL commands. The error occurs before the command runs — Claude Code fails to write output to its temp file.

Error

EINVAL: invalid argument, open 'C:\Users\User\AppData\Local\Temp\claude\...'

Behavior

• Some bash calls succeed in the same session
• Others fail with the above error
• Appears specific to certain WSL command structures
• Not a WSL problem — the command never executes; the failure is in Claude Code's temp file handling

Reproduction

Intermittent. Occurs during normal WSL bash usage on Windows 11. Have not isolated a specific trigger but it seems more likely with certain WSL commands than others.

Possible Causes

• Windows temp path handling issue
• Claude Code bug specific to Win11 + WSL2
• Something about the WSL command structure triggering the temp file write failure

Happy to provide more details if needed.