How to fix Error 3074 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 3074 occurs when SQL Server’s VSS (Volume Shadow Copy Service) writer attempts to retrieve file attributes from a database snapshot during a backup operation but fails to access the underlying file system metadata. This typically happens due to insufficient NTFS permissions on the snapshot volume, a corrupted or orphaned shadow copy, or interference from third-party backup/antivirus software intercepting file handles. It can also surface when the SQL Server service account lacks the necessary privileges to interact with the VSS provider on Windows Server 2025.

Step-by-Step Resolution Guide

Step 1: Verify VSS Service Health

  • Open an elevated Command Prompt and run vssadmin list writers to check if the SQL Server VSS Writer shows a “No error” state.
  • If the writer shows “Retryable error” or “Failed,” restart the service using net stop "SQL Server VSS Writer" followed by net start "SQL Server VSS Writer".
  • Check Event Viewer under Applications and Services Logs > Microsoft > Windows > VSS for correlating failure events.

Step 2: Clear Orphaned Shadow Copies

  • Run vssadmin list shadows to identify stale or orphaned snapshots tied to the database volume.
  • Delete problematic shadow copies with vssadmin delete shadows /for=<VolumeLetter>: /oldest.
  • Ensure there is adequate free space (at least 10% of volume size) reserved for shadow storage using vssadmin list shadowstorage.

Step 3: Validate Permissions on SQL Server Service Account

  • Navigate to SQL Server Configuration Manager > SQL Server Services and confirm the service account used (e.g., NT Service\MSSQLSERVER).
  • Grant this account Full Control on the database file directory (typically C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA) via file Properties > Security > Edit.
  • Also confirm the account is a member of the local Backup Operators group to allow snapshot attribute access.

Step 4: Check for Third-Party Software Interference

  • Temporarily disable antivirus or third-party backup agents (e.g., Veeam, Commvault) that may lock snapshot files during the VSS freeze/thaw cycle.
  • Add exclusions for SQL Server data/log directories and the %SystemDrive%\System Volume Information folder in your antivirus configuration.
  • Retry the backup job immediately after disabling the conflicting service to confirm resolution.

Step 5: Repair SQL Server VSS Writer Registration

  • If the writer remains unresponsive, re-register the VSS writer DLL by running regsvr32 sqlvdi.dll from the SQL Server Binn directory in an elevated prompt.
  • Restart the SQL Server service and the VSS service afterward to apply changes cleanly.

Alternative or Verification Steps

  • Re-run vssadmin list writers and confirm the SQL Server Writer state reads “Stable” with “No error” before initiating another snapshot-based backup.
  • If the issue persists, switch the backup method from VSS-based snapshot to native SQL Server full backup (BACKUP DATABASE ... TO DISK) as a temporary workaround while investigating storage-level snapshot driver issues.