Why do I see 524 errors on Langfuse API calls?

The 524 error class on Langfuse Cloud indicates that your request timed out because ClickHouse ran out of resources or out of time while processing your query. This typically occurs when queries scan too much data due to overly broad filter conditions. The main patch for those errors is adding narrow time-frame conditions to reduce the amount of data to be scanned.

General Approaches

To prevent 524 errors across all API endpoints:

1. Always use timestamp filters: Add fromTimestamp and toTimestamp parameters to limit the time range
2. Add specific filters: Use userId, sessionId, name, tags, or other filters to narrow your query

Optimizations for GET /api/public/traces

The GET /api/public/traces endpoint is particularly susceptible to 524 errors. Follow these best practices:

• Add timestamp filters: E.g. run GET /api/public/traces?page=1&limit=10&fromTimestamp=2025-10-16T00:00:00.000Z&toTimestamp=2025-10-17T00:00:00.000Z.
• Use the fields parameter: Request only the data you need to avoid expensive joins (e.g. GET /api/public/traces?fields=core,io).