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For side-by-side syntax and behavior across database engines, browse the cross-database SQL comparison guides.

MySQL Error 2006: MySQL Server Has Gone Away

Fix MySQL Error 2006 by checking idle connection timeouts, max_allowed_packet, server restarts, and stale application connections.

MySQL Error 2013: Lost Connection During Query

Troubleshoot MySQL Error 2013 by distinguishing initial connection timeouts from query-time network drops, transfer stalls, and large packets.

MySQL Error 2026: SSL Connection Error

Troubleshoot MySQL Error 2026 by checking certificate trust, host-name verification, TLS versions and ciphers, and account certificate requirements.

PostgreSQL Error 08006: Connection Failure

Troubleshoot PostgreSQL SQLSTATE 08006 by checking server restarts, network interruptions, keepalives, and uncertain transaction outcomes.

PostgreSQL Error 23503: Foreign Key Violation

Diagnose PostgreSQL SQLSTATE 23503 by checking missing parent rows, blocked parent deletes, and existing rows that violate a new foreign key.

PostgreSQL Error 23505: Duplicate Key Violates Unique Constraint

Diagnose PostgreSQL SQLSTATE 23505 by identifying the unique key, finding conflicting rows, and choosing an intentional ON CONFLICT action.

PostgreSQL Error 25P02: Current Transaction Is Aborted

Fix PostgreSQL SQLSTATE 25P02 by finding the first error in the transaction, then rolling back or recovering to a savepoint.

PostgreSQL Error 28P01: Password Authentication Failed

Troubleshoot PostgreSQL SQLSTATE 28P01 by checking the connection target, role, stored secret, and matching pg_hba.conf rule.

PostgreSQL Error 40001: Serialization Failure

Fix PostgreSQL SQLSTATE 40001 by identifying transaction isolation conflicts and retrying the complete transaction from a fresh snapshot.

PostgreSQL Error 40P01: Deadlock Detected

Troubleshoot PostgreSQL SQLSTATE 40P01 by identifying conflicting transactions, using consistent lock order, and retrying safely.