LiteLLM / LiteLLM
LiteLLM proxy team-scoped model fallback fails with public-to-internal name mismatch
Fix LiteLLM proxy fallback not triggering for team-scoped BYOK models due to public vs internal model name mismatch in Router.async_function_with_fallbacks Includes evidence for LiteLLM troubleshooting demand.
- Category
- LiteLLM
- Error signature
No fallback model group found for original model_group=primary. Available Model Group Fallbacks=None- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
No fallback model group found for original model_group=primary. Available Model Group Fallbacks=None is a LiteLLM failure pattern reported for developers trying to fix litellm proxy fallback not triggering for team-scoped byok models due to public vs internal model name mismatch in router.async_function_with_fallbacks. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
GitHub issue #28019 on BerriAI/litellm documents a routing bug: POST /fallback requires internal model names (model_name_team_uuid) but runtime requests use public names (e.g. gpt-4.1). The fallback lookup does direct string comparison before name resolution, so it never matches. Root cause identified in code (Router.async_function_with_fallbacks). Workaround available via model_aliases. Strong commercial value — directly impacts production proxy billing and failover reliability.
Common causes
- GitHub issue #28019 on BerriAI/litellm documents a routing bug: POST /fallback requires internal model names (model_name_team_uuid) but runtime requests use public names (e.g. gpt-4.1). The fallback lookup does direct string comparison before name resolution, so it never matches. Root cause identified in code (Router.async_function_with_fallbacks). Workaround available via model_aliases. Strong commercial value — directly impacts production proxy billing and failover reliability.
Quick fixes
- Confirm the exact error signature matches
No fallback model group found for original model_group=primary. Available Model Group Fallbacks=None. - 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: GitHub issue #28019 on BerriAI/litellm documents a routing bug: POST /fallback requires internal model names (model_name_team_uuid) but runtime requests use public names (e.g. gpt-4.1). The fallback lookup does direct string comparison before name resolution, so it never matches. Root cause identified in code (Router.async_function_with_fallbacks). Workaround available via model_aliases. Strong commercial value — directly impacts production proxy billing and failover reliability.
Related errors
- LiteLLM
FAQ
What should I check first?
Start with the exact No fallback model group found for original model_group=primary. Available Model Group Fallbacks=None 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 No fallback model group found for original model_group=primary. Available Model Group Fallbacks=None.