Fixing PgBouncer Authentication Errors: SCRAM-SHA-256 vs. MD5 Mismatch
Are you seeing the dreaded FATAL: server login has been failing error in your PgBouncer logs? If you recently updated your PostgreSQL user passwords and are now seeing (nouser) connection drops, you have likely run into an authentication mismatch between SCRAM-SHA-256 and MD5.
In this video, we diagnose why this happens and walk you through two clear methods to resolve it. Whether you need to revert to MD5 for legacy compatibility or want to upgrade your infrastructure to support the more secure SCRAM-SHA-256 authentication, this guide covers the exact commands and configuration steps required.
In this video, we cover:
0:00 – Intro: Understanding the PgBouncer Authentication Mismatch
0:45 – Identifying the issue (Environment & Error Logs)
1:30 – Root Cause: Why SCRAM vs. MD5 triggers the outage
2:15 – Method 1: Reverting to MD5 (for quick recovery)
3:30 – Method 2: Upgrading to SCRAM-SHA-256 (the modern standard)
4:45 – Summary & Best Practices
Key Takeaways:
Why auth_type in pgbouncer.ini must match your password encryption.
How to extract hashes from pg_shadow vs. pg_authid.
Step-by-step instructions for updating userlist.txt.
#PostgreSQL #PgBouncer #DatabaseAdministration #DevOps #TechTutorial #DataEngineering #SCRAM #MD5