How to fix Error 1475 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 1475 — Bulk Logged Changes Not Backed Up

Why This Error Happens

This error occurs because the database is operating under the Bulk-Logged recovery model, and minimally-logged operations (such as BULK INSERT, SELECT INTO, or index rebuilds) have been performed on the principal/primary database without a subsequent log backup. SQL Server blocks the mirroring or Always On synchronization process because it cannot guarantee the data pages affected by these bulk operations can be safely transmitted and applied to the mirror/secondary replica. Essentially, the transaction log contains data that exists only as pointers to the data file, not fully-logged transactional records, making it unsafe to continue the synchronization chain until a backup captures those actual data pages.

Step-by-Step Resolution Guide

Step 1: Identify the Current Recovery Model

  • Open SQL Server Management Studio (SSMS) and connect to the Principal/Primary instance.
  • Run the following query to check the current state:
  SELECT name, recovery_model_desc FROM sys.databases WHERE name = 'YourDatabaseName';
  • Confirm if the model is set to BULK_LOGGED.

Step 2: Take an Immediate Transaction Log Backup

  • Navigate to the backup directory (e.g., D:\SQLBackups\LogBackups\) to ensure sufficient disk space is available.
  • Execute a manual log backup to flush the bulk-logged extents into a physical backup file:
  BACKUP LOG [YourDatabaseName] 
  TO DISK = N'D:\SQLBackups\LogBackups\YourDatabaseName_LogFix.trn' 
  WITH NOFORMAT, NOINIT;
  • Wait for the command to complete successfully (Msg: “Processed X pages for database…”).

Step 3: Restore the Backup on the Secondary/Mirror

  • Copy the .trn file generated in Step 2 to the Secondary or Mirror server.
  • Restore the log file using the WITH NORECOVERY option to maintain the restore chain:
  RESTORE LOG [YourDatabaseName] 
  FROM DISK = N'D:\SQLBackups\LogBackups\YourDatabaseName_LogFix.trn' 
  WITH NORECOVERY;
  • Verify that the Mirroring/Availability Group dashboard in SSMS shows “Synchronized” or “Synchronizing” status.

Step 4: Switch Recovery Model to Prevent Recurrence

  • To avoid this issue in high-availability environments going forward, change the recovery model back to FULL.
  • Run this command on the Principal database:
  ALTER DATABASE [YourDatabaseName] SET RECOVERY FULL;
  • Note: BULK_LOGGED should only be used temporarily during massive ETL jobs and switched back to FULL immediately afterward.

Alternative or Verification Steps

  • Verification: Check the Always On Availability Groups dashboard or the Database Mirroring Monitor in SSMS to confirm the “Synchronization Health” status reads green/healthy and the error log no longer logs Event ID 1475.
  • Alternative: If a manual log backup is not feasible due to disk space constraints, configure a temporary backup job to a network share (UNC path) to capture the log, then immediately delete the file post-restoration to clear local disk space.