How to fix Error 3302 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 3302 – Redo Operation Failure During Recovery

Why This Error Happens

Error 3302 occurs when SQL Server’s recovery process cannot successfully redo logged transactions up to the expected Log Sequence Number (LSN), typically because the transaction log file has become physically corrupted or truncated unexpectedly. This often results from underlying storage failures, abrupt power loss during a write operation, antivirus software locking or modifying the .ldf file, or a faulty disk subsystem that failed to flush pages correctly. In virtualized or cloud environments, this can also stem from storage snapshot inconsistencies taken while the database was online.

Step-by-Step Resolution Guide

Step 1: Isolate the Database and Check Storage Health

  • Immediately take the database offline or set it to EMERGENCY mode to prevent further writes: ALTER DATABASE [YourDB] SET EMERGENCY;
  • Check the Windows Event Viewer (System and Application logs) for Disk, NTFS, or Volume Shadow Copy (VSS) errors around the timestamp of the failure.
  • Run chkdsk C: /f /r (replace with the correct drive letter hosting your .mdf/.ldf files) to rule out underlying disk corruption.

Step 2: Attempt Emergency-Mode Repair

  • Set the database to single-user mode to perform consistency checks: ALTER DATABASE [YourDB] SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
  • Run DBCC CHECKDB (YourDB, REPAIR_ALLOW_DATA_LOSS) to attempt to rebuild the log and fix internal corruption.
  • Note: This step may result in data loss for transactions that were in-flight at the time of the corruption.

Step 3: Restore from a Verified Full Backup

  • Since Error 3302 explicitly indicates the log cannot be trusted for redo operations, locate your most recent verified full backup file (e.g., D:\SQLBackups\YourDB_Full.bak).
  • Use SQL Server Management Studio (SSMS) 21 or T-SQL to restore the backup: RESTORE DATABASE [YourDB] FROM DISK = 'D:\SQLBackups\YourDB_Full.bak' WITH REPLACE;
  • If available, apply subsequent differential and transaction log backups sequentially using WITH NORECOVERY until the final log backup, which should use WITH RECOVERY.

Step 4: Harden the Environment Against Future Corruption

  • Exclude the SQL Server data directories (default: C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA) from any active antivirus or Windows Defender real-time scanning policies.
  • Verify that the storage controller’s write-caching policy is configured correctly (ensure “write-back” cache has battery backup/UPS protection) to prevent unflushed writes during power events.

Alternative or Verification Steps

  • Verify the Fix: After restoration, run DBCC CHECKDB (YourDB) WITH NO_INFOMSGS, ALL_ERRORMSGS; to confirm zero allocation or consistency errors exist before bringing the database back online for users.
  • Alternative Solution: If no full backup exists and REPAIR_ALLOW_DATA_LOSS fails, utilize a third-party log reader or the “Stellar/ApexSQL” recovery toolset to manually extract transaction data from the corrupted .ldf file before rebuilding the database schema from scratch.