5 posts tagged with "incident-report"

Date: Feb 23, 2026
Duration: ~3 hours
Severity: High (for users with provider wildcard access rules)
Status: Resolved

Summary​

When a new Anthropic model (e.g. claude-sonnet-4-6) was added to the LiteLLM model cost map and a cost map reload was triggered, requests to the new model were rejected with:

key not allowed to access model. This key can only access models=['anthropic/*']. Tried to access claude-sonnet-4-6.

The reload updated litellm.model_cost correctly but never re-ran add_known_models(), so litellm.anthropic_models (the in-memory set used by the wildcard resolver) remained stale. The new model was invisible to the anthropic/* wildcard even though the cost map knew about it.

• LLM calls: All requests to newly-added Anthropic models were blocked with a 401.
• Existing models: Unaffected — only models missing from the stale provider set were impacted.
• Other providers: Same bug class existed for any provider wildcard (e.g. openai/*, gemini/*).

Date: January 22, 2026 Duration: ~4 days (until fix merged January 26, 2026) Severity: High Status: Resolved

Note: This fix is available starting from LiteLLM v1.81.3.rc.6 or higher.

Summary​

A PR (#19467) accidentally removed the root_path=server_root_path parameter from the FastAPI app initialization in proxy_server.py. This caused the proxy to ignore the SERVER_ROOT_PATH environment variable when serving the UI. Users who deploy LiteLLM behind a reverse proxy with a path prefix (e.g., /api/v1 or /llmproxy) found that all UI pages returned 404 Not Found.

• LLM API calls: No impact. API routing was unaffected.
• UI pages: All UI pages returned 404 for deployments using SERVER_ROOT_PATH.
• Swagger/OpenAPI docs: Broken when accessed through the configured root path.

Date: Feb 16, 2026 Duration: ~3 hours Severity: High (for vLLM embedding users) Status: Resolved

Summary​

A commit (dbcae4a) intended to fix OpenAI SDK behavior broke vLLM embeddings by explicitly passing encoding_format=None in API requests. vLLM rejects this with error: "unknown variant \`, expected float or base64"`.

• vLLM embedding calls: Complete failure - all requests rejected
• Other providers: No impact - OpenAI and other providers functioned normally
• Other vLLM functionality: No impact - only embeddings were affected

Date: February 13, 2026 Duration: ~3 hours Severity: High Status: Resolved

Note: This fix will be available starting from v1.81.13-nightly or higher of LiteLLM.

Summary​

Claude Code began sending unsupported Anthropic beta headers to non-Anthropic providers (Bedrock, Azure AI, Vertex AI), causing invalid beta flag errors. LiteLLM was forwarding all beta headers without provider-specific validation. Users experienced request failures when routing Claude Code requests through LiteLLM to these providers.

• LLM calls to Anthropic: No impact.
• LLM calls to Bedrock/Azure/Vertex: Failed with invalid beta flag errors when unsupported headers were present.
• Cost tracking and routing: No impact.

Date: January 27, 2026 Duration: ~20 minutes Severity: Low Status: Resolved

Summary​

A malformed JSON entry in model_prices_and_context_window.json was merged to main (562f0a0). This caused LiteLLM to silently fall back to a stale local copy of the model cost map. Users on older package versions lost cost tracking for newer models only (e.g. azure/gpt-5.2). No LLM calls were blocked.

• LLM calls and proxy routing: No impact.
• Cost tracking: Impacted for newer models not present in the local backup. Older models were unaffected. The incident lasted ~20 minutes until the commit was reverted.