What this error means

API Error: 400 "You're out of extra usage" is a Claude Code failure pattern reported for developers trying to fix claude code routing api requests to extra usage billing instead of max plan quota. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

521 reactions on GitHub. Reproducible with minimal test: commit message containing 'HERMES.md' routes to extra usage billing. Affects Max 20x ($200/month) plan users. Server-side routing triggered by string in commit history.

Common causes

  • Git commit messages containing 'HERMES.md' silently trigger extra usage billing on Claude Code Max 20x plan, burning through $200+ while plan quota sits unused
  • 521 reactions on GitHub. Reproducible with minimal test: commit message containing 'HERMES.md' routes to extra usage billing. Affects Max 20x ($200/month) plan users. Server-side routing triggered by string in commit history.

Quick fixes

  1. Confirm the exact error signature matches API Error: 400 "You're out of extra usage".
  2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
  3. Reduce request pressure, check quota or plan limits, and retry with backoff instead of immediate repeated requests.

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.