How to fix Error 4308 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 4308 typically surfaces during a piecemeal (online) restore sequence in SQL Server 2025 when a filegroup is brought online before all required transaction log backups have been applied. The message “The online restore is complete” is misleading—it indicates that an individual restore step finished, but the overall recovery chain is still broken because a subsequent log file is missing, corrupted, or was restored out of order. This commonly occurs when backup files sit on a network share with inconsistent NTFS/share permissions for the SQL Server service account, or when a backup set was truncated during copy.

Step-by-Step Resolution Guide

Step 1: Verify the Restore Sequence

  • Run RESTORE HEADERONLY FROM DISK = 'path\to\backup.trn' against every log backup in the chain to confirm LSNs are contiguous.
  • Check sys.master_files and msdb.dbo.restorehistory to identify which filegroup is still flagged as RESTORING.
  • Confirm no log backup is missing between the full backup and the point of failure.

Step 2: Validate File and Share Permissions

  • Ensure the SQL Server service account (visible in SQL Server Configuration Manager) has Read and Read & Execute NTFS permissions on the backup folder, typically C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Backup\.
  • If backups are on a network share, confirm the share permissions match the NTFS permissions exactly (no “Everyone = Read” mismatches).
  • Restart the SQL Server (MSSQLSERVER) service after any permission change via services.msc or Restart-Service MSSQLSERVER in PowerShell.

Step 3: Re-run the Restore with NORECOVERY

  • Re-issue the restore command explicitly specifying WITH NORECOVERY for all intermediate logs:
  RESTORE LOG [YourDB] FROM DISK = 'D:\Backups\log1.trn' WITH NORECOVERY;
  • Only use WITH RECOVERY on the final log in the chain to bring the filegroup fully online.
  • If a backup file is confirmed corrupted (via RESTORE VERIFYONLY), source a fresh copy from the backup repository before resuming.

Step 4: Check Windows Server 2025 File System Health

  • Run chkdsk D: /f (replace D: with the backup drive) during a maintenance window to rule out underlying disk corruption affecting the .bak/.trn files.
  • Review Event Viewer > Windows Logs > System for disk or storage controller errors around the time of the restore.

Alternative or Verification Steps

  • After completing the sequence, run RESTORE DATABASE [YourDB] WITH RECOVERY; and confirm the database state changes from RESTORING to ONLINE via SELECT state_desc FROM sys.databases WHERE name = 'YourDB';.
  • If error 4308 persists, perform a full STANDBY restore instead of NORECOVERY to inspect the database state without fully committing, then replay logs one at a time to isolate the corrupted file.