Langfuse Common Errors Overview Diagnostic reference for the 10 most common Langfuse integration errors, with real error messages, root causes, and tested solutions. Prerequisites - Langfuse SDK installed - API credentials configured - Access to application logs or console output Error Reference 1. Authentication Failed (401) Error: Cause: API key missing, expired, revoked, or keys from wrong project. Fix: 2. Traces Not Appearing in Dashboard Symptom: Code runs without errors but no traces show in UI. Root causes (in order of likelihood): 1. Data not flushed before process exits 2. Wrong proj…