How to fix Error 3269 on Windows Server 2025 / Windows 11

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Why This Error Happens

This error occurs because SQL Server backup files store metadata about the physical sector size of the device they were originally written to, and this value is validated during restore operations. When the backup media (originally written on a device with 512-byte or 4K sector alignment) is restored to a target device with a different sector size, SQL Server blocks the operation to prevent data corruption or I/O misalignment. This commonly happens when backups are moved between physical disks, SANs, virtual disks, or cloud storage (such as Azure Blob or VHDX-based volumes) that use Advanced Format (4Kn) drives instead of legacy 512-byte emulation (512e) drives.

Step-by-Step Resolution Guide

Step 1: Identify the Sector Size Mismatch

  • Run fsutil fsinfo sectorinfo <DriveLetter>: in an elevated Command Prompt on both the source and target systems.
  • Compare the “Physical Bytes Per Sector” and “Logical Bytes Per Sector” values reported in the error message (%d and %d) to confirm the mismatch.
  • Note the exact file path referenced in the error (%ls) to confirm which backup file is affected.

Step 2: Restore Using a Compatible Intermediate Location

  • Copy the .bak or .trn file to a storage volume that matches the original sector size (e.g., move from a 4Kn NVMe drive to a 512e-formatted volume).
  • Use Robocopy or standard file copy tools rather than streaming the restore directly from the mismatched device.
  • Re-run the restore command once the file resides on compatible media:
  RESTORE DATABASE [YourDB] FROM DISK = 'D:\SQLBackups\YourDB.bak' WITH RECOVERY;

Step 3: Reformat or Reprovision the Target Disk

  • If the target server’s storage was provisioned with 4Kn sector size (common on newer NVMe/SSD hardware in Windows Server 2025), reformat the target volume using 512e emulation if your storage controller supports it.
  • In Disk Management or via PowerShell, check disk properties with:
  Get-PhysicalDisk | Select FriendlyName, PhysicalSectorSize, LogicalSectorSize
  • Reprovision the disk through your storage vendor’s management tool (SAN/NAS controller) to force 512e mode if 4Kn is not required for performance reasons.

Step 4: Use a Staging VM or Network Share as a Workaround

  • If reformatting is not feasible, stage the backup file on a network share (SMB) that abstracts the underlying sector size.
  • Perform the restore from the UNC path instead of a local 4Kn-formatted disk:
  RESTORE DATABASE [YourDB] FROM DISK = '\\FileServer\Backups\YourDB.bak' WITH RECOVERY;

Alternative or Verification Steps

  • After applying the fix, verify success by checking SQL Server Error Logs or re-running RESTORE HEADERONLY FROM DISK = '<path>' to confirm the file reads without triggering Error 3269.
  • As an alternative, use BACKUP DATABASE with COPY_ONLY on a 512e-compatible source system to generate a new backup file that matches the sector size of your current infrastructure.