LiteLLM Bedrock /v1/messages Fails — Missing compact-2026-01-12 Beta Header for Anthropic on Bedrock

What this error means

LiteLLM /v1/messages passes context_management to Bedrock without compact-2026-01-12 beta header is a LiteLLM failure pattern reported for developers trying to fix litellm /v1/messages endpoint failing with bedrock invokemodel due to missing compact beta header. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #27532: Root cause identified — LiteLLM /v1/messages endpoint passes context_management to Bedrock InvokeModel without injecting required compact-2026-01-12 beta header into anthropic_beta array. Affects Anthropic Claude models on AWS Bedrock via LiteLLM.

Common causes

• LiteLLM’s /v1/messages passthrough to Bedrock InvokeModel fails because it passes context_management through to Bedrock but does not inject the required compact-2026-01-12 beta header. This breaks Anthropic Claude models on AWS Bedrock when using LiteLLM proxy.
• GitHub issue #27532: Root cause identified — LiteLLM /v1/messages endpoint passes context_management to Bedrock InvokeModel without injecting required compact-2026-01-12 beta header into anthropic_beta array. Affects Anthropic Claude models on AWS Bedrock via LiteLLM.

Quick fixes

1. Confirm the exact error signature matches LiteLLM /v1/messages passes context_management to Bedrock without compact-2026-01-12 beta header.
2. Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
3. 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

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. 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

• https://github.com/BerriAI/litellm/issues/27532

Evidence note: GitHub issue #27532: Root cause identified — LiteLLM /v1/messages endpoint passes context_management to Bedrock InvokeModel without injecting required compact-2026-01-12 beta header into anthropic_beta array. Affects Anthropic Claude models on AWS Bedrock via LiteLLM.

Related errors

• LiteLLM Bedrock Anthropic model not found
• AWS Bedrock InvokeModel 400 error

FAQ

What should I check first?

Start with the exact LiteLLM /v1/messages passes context_management to Bedrock without compact-2026-01-12 beta header 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 /v1/messages passes context_management to Bedrock without compact-2026-01-12 beta header.