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.

Source-backed Last updated May 12, 2026 1 source Needs local verification

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: May 12, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for LiteLLM, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

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.

Diagnostic flow for this page

Match litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. exactly before applying the quick fix.
Compare the failing environment with LiteLLM versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. mean in LiteLLM?

litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. indicates the workflow described by "LiteLLM BadRequestError when using llm_as_a_judge guardrail with self-hosted vLLM model" failed in a LiteLLM context. Start by confirming the exact signature and the component that emitted it.

What should I check first for litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call.?

Check whether this cause matches your environment: 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.

Is the litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call. guidance source-backed?

The "LiteLLM BadRequestError when using llm_as_a_judge guardrail with self-hosted vLLM model" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call.?

For "LiteLLM BadRequestError when using llm_as_a_judge guardrail with self-hosted vLLM model", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging litellm.BadRequestError: LLM Provider NOT provided. Pass in the LLM provider you are trying to call.?

For "LiteLLM BadRequestError when using llm_as_a_judge guardrail with self-hosted vLLM model", collect the failing LiteLLM command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.