How to fix Error 5269 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 5269 – Transient Database Snapshot Marked Suspect

Why This Error Happens

Error 5269 occurs when SQL Server’s internal consistency checker (DBCC CHECKDB) creates a hidden, transient database snapshot to perform validation, but the underlying I/O subsystem fails while reading or writing sparse file data for that snapshot. This is typically caused by insufficient disk space on the volume hosting the snapshot sparse files, underlying storage corruption, antivirus/filter driver interference, or a failing disk/storage controller. Since the snapshot relies on NTFS sparse file technology, any interruption to the volume (permissions, storage latency, or disk health) during the CHECKDB operation causes the snapshot to be marked suspect and the check to terminate.

Step-by-Step Resolution Guide

Step 1: Verify Disk Space and Volume Health

  • Check the volume where the database data files reside (snapshot files are created in the same directory by default) for available free space.
  • Run Get-Volume in PowerShell or check Disk Management to confirm at least 2x the size of the largest data file is free.
  • Run chkdsk C: /f /r (replace with the correct drive letter) during a maintenance window to rule out underlying file system corruption.

Step 2: Review the SQL Server Error Log for Root Cause

  • Open SQL Server Management Studio (SSMS) and navigate to Management > SQL Server Logs, or review the log file directly at C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG.
  • Look for accompanying OS-level errors such as Error 823, 824, or 825, which indicate specific I/O failures (e.g., “incorrect checksum” or “operating system error 1117”).
  • Note the specific file path mentioned for the sparse snapshot file (usually named with a .ss extension in the default data directory).

Step 3: Exclude SQL Server Directories from Antivirus/Filter Drivers

  • Open Windows Security or your third-party antivirus console on Windows Server 2025.
  • Add exclusions for the SQL Server data directory (e.g., C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA) and the tempdb location.
  • Restart the SQL Server (MSSQLSERVER) service via services.msc to ensure the exclusion takes effect before re-running the check.

Step 4: Run DBCC CHECKDB with Alternative Options

  • Instead of allowing SQL Server to create an automatic snapshot, force the check to run directly against the live database using the WITH TABLOCK option, which bypasses the snapshot creation mechanism: 
DBCC CHECKDB ('YourDatabaseName') WITH TABLOCK, NO_INFOMSGS;
  • Note that this will acquire locks and may block user activity, so schedule it during off-peak hours.

Step 5: Inspect Physical Storage and Drivers

  • Update storage controller and HBA drivers via Windows Update or the hardware vendor’s site, specifically for Windows Server 2025 compatibility.
  • Check the Windows Event Viewer under Windows Logs > System for Disk or Ntfs warnings that correlate with the timestamp of the SQL error.

Alternative or Verification Steps

  • Verify the Fix: Re-run DBCC CHECKDB ('YourDatabaseName') WITH NO_INFOMSGS, ALL_ERRORMSGS; and confirm it completes without Error 5269 or 823/824 I/O errors in the output.
  • Alternative Solution: If the issue persists on the same volume, move the database files (ALTER DATABASE ... MODIFY FILE) to a different physical disk or LUN to isolate whether the storage hardware is the root cause.