LiteLLM / LiteLLM
LiteLLM BadRequestError when using llm_as_a_judge guardrail with self-hosted vLLM model
Fix LiteLLM llm_as_a_judge guardrail failing with BadRequestError when using vLLM self-hosted model Includes evidence for LiteLLM troubleshooting demand.
- Category
- LiteLLM
- Error signature
litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call.- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. is a LiteLLM failure pattern reported for developers trying to fix litellm llm_as_a_judge guardrail failing with badrequesterror when using vllm self-hosted model. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
Official BerriAI/litellm GitHub issue (v1.83.14). Self-hosted vLLM model (google/gemma-4-31B-it) works in LiteLLM playground but fails with litellm.BadRequestError in llm_as_a_judge guardrail. Both vllm and OpenAI compatible endpoint providers affected. Kubernetes helm chart deployment.
Common causes
- Developers running self-hosted LLMs via vLLM through LiteLLM proxy encounter a BadRequestError when using the llm_as_a_judge guardrail feature. The model works fine for normal queries but fails specifically in guardrail evaluation, blocking AI safety/quality pipelines in production Kubernetes deployments.
- Official BerriAI/litellm GitHub issue (v1.83.14). Self-hosted vLLM model (google/gemma-4-31B-it) works in LiteLLM playground but fails with litellm.BadRequestError in llm_as_a_judge guardrail. Both vllm and OpenAI compatible endpoint providers affected. Kubernetes helm chart deployment.
Quick fixes
- Confirm the exact error signature matches
litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call.. - 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: Official BerriAI/litellm GitHub issue (v1.83.14). Self-hosted vLLM model (google/gemma-4-31B-it) works in LiteLLM playground but fails with litellm.BadRequestError in llm_as_a_judge guardrail. Both vllm and OpenAI compatible endpoint providers affected. Kubernetes helm chart deployment.
Related errors
- LiteLLM guardrail vLLM provider error
- LiteLLM llm_as_a_judge fails with custom endpoint
- LiteLLM provider not detected for self-hosted model
FAQ
What should I check first?
Start with the exact litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. 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 litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call..