LiteLLM / LiteLLM
LiteLLM Proxy Returns 400 Validation Errors on Claude Code Multi-Turn Conversations
Fix LiteLLM proxy 400 validation error when Claude Code sends multi-turn conversations Includes evidence for LiteLLM troubleshooting demand.
- Category
- LiteLLM
- Error signature
177 validation errors: Input should be a valid string- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
177 validation errors: Input should be a valid string is a LiteLLM failure pattern reported for developers trying to fix litellm proxy 400 validation error when claude code sends multi-turn conversations. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
Error: litellm.BadRequestError with 177 validation errors. Input should be a valid string but receiving complex message objects. Specific to Claude Code → LiteLLM proxy path.
Common causes
- Claude Code calls LiteLLM gateway and gets 400 with 177 validation errors about input types. LiteLLM proxy doesn’t correctly translate Claude Code’s message format. Multi-turn conversations get stuck.
- Error: litellm.BadRequestError with 177 validation errors. Input should be a valid string but receiving complex message objects. Specific to Claude Code → LiteLLM proxy path.
Quick fixes
- Confirm the exact error signature matches
177 validation errors: Input should be a valid string. - 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: Error: litellm.BadRequestError with 177 validation errors. Input should be a valid string but receiving complex message objects. Specific to Claude Code → LiteLLM proxy path.
Related errors
- LiteLLM Bedrock structured output failure
- Claude Code Unhandled case object Object
FAQ
What should I check first?
Start with the exact 177 validation errors: Input should be a valid string 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 177 validation errors: Input should be a valid string.