Claude Code Desktop Crashes with Bun Runtime Segfault (Exit Code 3)

What this error means

panic(main thread): Segmentation fault at address 0x40FE0 is a Claude Code failure pattern reported for developers trying to fix claude code desktop crash with segmentation fault in bun runtime on windows. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #58586 reports Claude Code desktop crashing on Windows 11 with ‘panic(main thread): Segmentation fault at address 0x40FE0’ in Bun v1.3.14. Exit code 3 on every launch. System: Intel i7-12850HX, 32GB RAM.

Common causes

• Claude Code desktop app (v2.1.138) on Windows crashes with a segmentation fault inside Bun v1.3.14 runtime, returning exit code 3. The crash occurs before the app can do anything useful. Developers need a workaround or fix to use the tool at all.
• GitHub issue #58586 reports Claude Code desktop crashing on Windows 11 with ‘panic(main thread): Segmentation fault at address 0x40FE0’ in Bun v1.3.14. Exit code 3 on every launch. System: Intel i7-12850HX, 32GB RAM.

Quick fixes

1. Confirm the exact error signature matches panic(main thread): Segmentation fault at address 0x40FE0.
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/claude-code/issues/58586

Evidence note: GitHub issue #58586 reports Claude Code desktop crashing on Windows 11 with ‘panic(main thread): Segmentation fault at address 0x40FE0’ in Bun v1.3.14. Exit code 3 on every launch. System: Intel i7-12850HX, 32GB RAM.

Related errors

• Claude Code exit code 3 Windows
• Bun runtime crash Claude Code

FAQ

What should I check first?

Start with the exact panic(main thread): Segmentation fault at address 0x40FE0 text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without panic(main thread): Segmentation fault at address 0x40FE0.