How to fix Error 4355 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 4355 – Invalid RESTORE Revert Command

Why This Error Happens

Error 4355 occurs when the RESTORE DATABASE ... FROM DATABASE_SNAPSHOT syntax is malformed, typically due to incorrect database name casing, missing brackets around identifiers with special characters, or an improperly referenced snapshot name. This error can also surface when the target database has multiple snapshots and the engine cannot resolve which snapshot to revert to because the T-SQL command omits the fully qualified snapshot identifier. Additionally, corrupted metadata in sys.databases referencing a stale or deleted snapshot can trigger this syntax validation failure even when the command appears correct.

Step-by-Step Resolution Guide

Step 1: Verify the Exact RESTORE Syntax

  • Confirm the command follows the exact pattern: RESTORE DATABASE YourDatabaseName FROM DATABASE_SNAPSHOT = 'YourSnapshotName';
  • Ensure both database and snapshot names are enclosed in single quotes if they contain spaces, hyphens, or special characters.
  • Run the query directly in SSMS (SQL Server Management Studio) connected to the Database Engine, not through a GUI wizard that may auto-generate malformed syntax.

Step 2: Validate the Snapshot Exists and Is Accessible

  • Open a new query window and run:
  SELECT name, source_database_id, create_date 
  FROM sys.databases 
  WHERE source_database_id IS NOT NULL;
  • Confirm the snapshot name returned matches exactly what you are specifying in the RESTORE command (case sensitivity matters if the instance uses a case-sensitive collation).
  • If the snapshot does not appear, it may have been deleted or never created successfully — recreate it using CREATE DATABASE YourSnapshotName ON (NAME = YourDataFile, FILENAME = 'C:\SQLData\YourSnapshot.ss') AS SNAPSHOT OF YourDatabaseName;

Step 3: Check for Multiple Snapshots on the Same Database

  • Run sp_helpdb YourDatabaseName or query sys.databases to check if more than one snapshot exists for the source database.
  • SQL Server 2025 requires you to explicitly pick one snapshot when multiples exist; the RESTORE command will fail with 4355 if the snapshot name is ambiguous or omitted.
  • Drop any obsolete or duplicate snapshots using DROP DATABASE YourOldSnapshotName; to reduce ambiguity.

Step 4: Restart the SQL Server Service and Clear Cached Plans

  • Open Services.msc on Windows Server 2025 / Windows 11 and restart the SQL Server (MSSQLSERVER) service (or named instance equivalent).
  • Alternatively, run DBCC FREEPROCCACHE; in SSMS to clear any cached execution plans that may be referencing outdated snapshot metadata.
  • Re-run the corrected RESTORE command after the service restart completes.

Alternative or Verification Steps

  • Verify the fix by querying sys.databases again post-restore to confirm the database state_desc shows ONLINE and the snapshot reference is removed (since reverting consumes the snapshot).
  • If the error persists, drop and recreate the snapshot from scratch, then immediately attempt the revert without any delay, as stale snapshot file handles on Windows Server 2025 can sometimes cause transient metadata mismatches.