Windows native CLI 2.1.250 launches embedded Bun instead of Claude Code
Preflight Checklist
- [x] I have searched existing issues and this hasn't been reported yet.
- [x] This is a single bug report (please file separate reports for different bugs).
- [x] I am using the latest version of Claude Code.
What's Wrong?
After the native Windows auto-update, claude launches the embedded Bun CLI rather than Claude Code. The command resolves directly to the native claude.exe; it is not a PowerShell alias or PATH conflict.
What Should Happen?
Claude Code should start normally, and claude --version should report the Claude Code version rather than the embedded Bun runtime version.
Error Messages/Logs
ext
Bun is a fast JavaScript runtime, package manager, bundler, and test runner. (1.4.1+392624bed)
claude --version outputs:
ext
1.4.1
Steps to Reproduce
- On Windows, install or auto-update the native Claude Code CLI to the affected release.
- Open PowerShell.
- Run claude or claude --version.
- The executable starts Bun instead of Claude Code.
Claude Model
Not applicable: the CLI fails before a model can be selected.
Is this a Regression?
Yes, this worked in a previous version. The failure started after the 2026-08-28 auto-update.
Last Working Version
Previous installed executable: 2.1.247 (the auto-updater retained it as a backup).
Claude Code Version
The executable's file metadata reports Claude Code 2.1.250.0 (InternalName: bun). At runtime, claude --version incorrectly reports 1.4.1, the embedded Bun version.
Platform
Other — not reached; the CLI fails before authentication or API-platform selection.
Operating System
Windows.
Terminal/Shell
PowerShell.
Additional Information
- The executable was auto-updated on 2026-08-28 at 14:49 local time.
- BUN_BE_BUN is absent from the current, User, and Machine environments.
- This matches earlier Windows packaging regressions where the native Claude binary booted into Bun instead of its bundled Claude entrypoint.