How to fix Error 3073 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 3073 – WITH FILE_SNAPSHOT Restriction in SQL Server 2025

Why This Error Happens

This error occurs because the WITH FILE_SNAPSHOT option for BACKUP or RESTORE operations requires that every single database file (data and log files) reside in Azure Blob Storage. SQL Server performs a validation check prior to execution, and if even one file in the database resides on local disk, a UNC path, or a non-Azure storage account, the engine rejects the entire operation and throws Error 3073. This commonly happens during hybrid migrations where a database has a mix of local .mdf/.ldf files and Azure-based .ndf files, or when a backup script is copy-pasted from an Azure-only environment into an on-premises instance.

Step-by-Step Resolution Guide

Step 1: Verify File Locations for the Target Database

  • Run the following query to inspect all file paths associated with the database:
  SELECT name, physical_name, type_desc 
  FROM sys.master_files 
  WHERE database_id = DB_ID('YourDatabaseName');
  • Check the physical_name column for any path that does not start with https://<storageaccount>.blob.core.windows.net/.
  • Flag any paths pointing to local drives (e.g., C:\, D:\) or on-premises UNC shares (e.g., \\FileServer\SQLData\).

Step 2: Migrate Remaining Local Files to Azure Storage

  • If local files were found in Step 1, you must move them to Azure Blob Storage before using FILE_SNAPSHOT.
  • Create a SQL Server Credential for the Azure Storage Account:
  CREATE CREDENTIAL [https://yourstorageaccount.blob.core.windows.net/yourcontainer]
  WITH IDENTITY = 'SHARED ACCESS SIGNATURE',
  SECRET = 'sv=2025-01-01&ss=b&srt=sco&sp=rwdlac...';
  • Use a standard BACKUP/RESTORE (without FILE_SNAPSHOT) to move the database file-by-file, or use ALTER DATABASE ... MODIFY FILE to relocate the physical file to a new Azure URL, followed by taking the file offline and copying the data via AzCopy.

Step 3: Remove the FILE_SNAPSHOT Clause for Hybrid Backups

  • If migrating the file to Azure is not immediately feasible, modify your T-SQL script to remove the incompatible option.
  • Update your backup command to use a standard backup syntax instead:
  BACKUP DATABASE [YourDatabaseName] 
  TO URL = 'https://yourstorageaccount.blob.core.windows.net/yourcontainer/backup.bak';
  • Note that standard backups to a URL do not support instantaneous snapshot restores but will bypass the Error 3073 validation check entirely.

Step 4: Check for Orphaned or Stale File Metadata

  • Sometimes a file is moved to Azure, but the SQL Server metadata catalog retains an old local cache reference.
  • Restart the SQL Server service to clear the metadata cache:
  Restart-Service -Name 'MSSQLSERVER' -Force
  • Re-run the query from Step 1 to ensure the sys.master_files catalog reflects the updated Azure URL paths accurately.

Alternative or Verification Steps

  • Verification: Once all files are confirmed to be in Azure Storage via sys.master_files, re-attempt the BACKUP DATABASE ... WITH FILE_SNAPSHOT command; it should now complete without throwing Error 3073.
  • Alternative: If a fully Azure-based architecture isn’t required, use Storage Spaces Direct (S2D) or local VSS-based snapshots via a third-party agent instead of the native FILE_SNAPSHOT T-SQL option to achieve similar fast-restore capabilities on-premises.