How to Diagnose a 500 Error in an ASP.NET Core API in Production

When a 500 appears in production, I follow a simple path:

• Scope the impact – single user, endpoint or system-wide?
• Grab the correlation ID – from X-Correlation-Id or logs.
• Check structured logs – endpoint, exception type, stack trace, key IDs.
• Reproduce safely – same payload in staging/local, aligned config and DB.
• Fix the root cause – unhandled exceptions, EF Core/SQL issues, misconfig, or failing external services.
• Deploy, monitor, document – watch logs/metrics and record cause + fix.

Over time, this turns 500s from panic into a repeatable, calm investigation process.

3 min read • Published Nov 30, 2025