SQL log chain break: detection and repair

Overview

Transaction log backups must be an unbroken chain until a full; breaks mean cannot restore to point-in-time.

Detection

Backup job warnings, SQL errorlog “BACKUP LOG cannot be performed” due to recovery model changes.

Common causes

Switching to SIMPLE during maintenance and forgetting; rogue SHRINK after bulk load without log backup.

Repair path

Take fresh FULL backup after stabilization; document gap accepted by business.

Prevention

Change control on recovery model; monitoring alert on model drift.

Client comms

Explain data loss window if chain unrecoverable—get written acknowledgment.