[BUG] WSL1: claude 2.1.83/2.1.84 fail with "Exec format error" while 2.1.81 works

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?

Description

On WSL1, claude CLI version 2.1.83 and 2.1.84 both fail with Exec format error, while 2.1.81 works fine and all other Linux binaries on the same distro run without issue.

Exact error:

-bash: /home/nils/.local/bin/claude: cannot execute binary file: Exec format error

This is not an architecture mismatch or wrong‑OS binary; the file reports as a valid x86‑64 ELF and ldd shows normal linkage.

Environment

• OS: Windows 10
• WSL: WSL1 (not WSL2)
• Distro: Ubuntu 22.04 LTS
• Shell: bash
• claude installed via: curl -sSL https://get.claudecode.com | bash

Diagnostics

uname -m
# x86_64

file ~/.local/bin/claude
# output: symbolic link to /home/nils/.local/share/claude/versions/2.1.84

file /home/nils/.local/share/claude/versions/2.1.84
# output: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, ...

ldd /home/nils/.local/share/claude/versions/2.1.84
# normal output (libc, pthread, etc.)

Other binaries (including 2.1.81) show identical file/ldd output but do not trigger Exec format error.

What Should Happen?

Expected behavior

2.1.83 and 2.1.84 should behave like 2.1.81 and execute normally on WSL1, since the binary is a valid x86‑64 Linux ELF.

Error Messages/Logs

Steps to Reproduce

Steps to reproduce

1. Install claude-code 2.1.81 in WSL1:

• claude --version → works.
• claude --help → works.

1. Install claude-code 2.1.83 or 2.1.84 in WSL1 (same machine, same distro).
2. Run:

``bash
claude --version # or /home/nils/.local/bin/claude --version
`
Result:
`bash
-bash: /home/nils/.local/bin/claude: cannot execute binary file: Exec format error
``

1. All other ELF binaries (e.g. /usr/bin/ls, /usr/bin/echo) work fine.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.81

Claude Code Version

2.1.84

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

Notes

• This occurs only on WSL1; 2.1.83/2.1.84 work fine on WSL2.