LiteLLM / LiteLLM
LiteLLM /v1/responses/compact Fails During Fallback with 'Unknown parameter: metadata'
Fix LiteLLM fallback failure when /v1/responses/compact endpoint returns 400 Unknown parameter metadata Includes evidence for LiteLLM troubleshooting demand.
- Category
- LiteLLM
- Error signature
/v1/responses/compact fails during router_settings.fallbacks — Unknown parameter: metadata- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
/v1/responses/compact fails during router_settings.fallbacks — Unknown parameter: metadata is a LiteLLM failure pattern reported for developers trying to fix litellm fallback failure when /v1/responses/compact endpoint returns 400 unknown parameter metadata. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
/v1/responses/compact fails during router_settings.fallbacks failover from primary to fallback model, with Azure returning 400 ‘Unknown parameter: metadata’. Hardcoded metadata key in run_async_fallback causes the error.
Common causes
- LiteLLM is a widely used API proxy for routing between multiple LLM providers. Fallback failures mean production AI services degrade without proper error handling.
- /v1/responses/compact fails during router_settings.fallbacks failover from primary to fallback model, with Azure returning 400 ‘Unknown parameter: metadata’. Hardcoded metadata key in run_async_fallback causes the error.
Quick fixes
- Confirm the exact error signature matches
/v1/responses/compact fails during router_settings.fallbacks — Unknown parameter: metadata. - Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
- 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
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- 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
Evidence note: /v1/responses/compact fails during router_settings.fallbacks failover from primary to fallback model, with Azure returning 400 ‘Unknown parameter: metadata’. Hardcoded metadata key in run_async_fallback causes the error.
Related errors
- LiteLLM Azure fallback error
- LiteLLM router_settings failed
- LiteLLM metadata parameter error
FAQ
What should I check first?
Start with the exact /v1/responses/compact fails during router_settings.fallbacks — Unknown parameter: metadata text and the smallest action that reproduces it.
Can I ignore this error?
No. Treat it as a failed LiteLLM 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 /v1/responses/compact fails during router_settings.fallbacks — Unknown parameter: metadata.