How to fix Error 4303 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: SQL Server Error 4303 — Roll Forward Start Point Incomplete

Why This Error Happens

This error occurs when SQL Server detects that the restore sequence is incomplete because the transaction log chain has a gap between the current roll forward LSN and the LSN required to bring the database to a consistent state. This is typically caused by restoring log backups out of order, skipping a required differential or log backup in the sequence, or attempting to recover the database (using WITH RECOVERY) before all necessary backups have been applied. It can also result from a missing or corrupted log backup file that breaks the continuity of the LSN chain.

Step-by-Step Resolution Guide

Step 1: Verify the Complete Backup Chain

  • Query msdb.dbo.backupset to list all full, differential, and log backups in chronological order for the affected database.
  • Run: SELECT backup_start_date, type, first_lsn, last_lsn, database_backup_lsn FROM msdb.dbo.backupset WHERE database_name = 'YourDB' ORDER BY backup_start_date
  • Confirm there are no missing log backup files between the last restored LSN and the target recovery point.

Step 2: Restart the Restore Sequence with NORECOVERY

  • Begin again from the most recent full backup using RESTORE DATABASE YourDB FROM DISK = 'C:\Backups\YourDB_Full.bak' WITH NORECOVERY.
  • Apply any differential backup using RESTORE DATABASE YourDB FROM DISK = 'C:\Backups\YourDB_Diff.bak' WITH NORECOVERY.
  • Restore every subsequent transaction log backup in exact chronological order, each WITH NORECOVERY, ensuring none are skipped.

Step 3: Locate and Apply Any Missing Log Backups

  • Check the backup file storage location (e.g., C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Backup\) for any .trn files that were not included in the restore script.
  • If a log backup file is missing or corrupted, check for a secondary copy on a backup server, Azure Blob Storage, or third-party backup tool repository.
  • Re-run the RESTORE LOG command for the missing LSN range once the file is located.

Step 4: Finalize Recovery

  • Once all log backups up to and including the required LSN are applied, run RESTORE DATABASE YourDB WITH RECOVERY to bring the database online.
  • Confirm no further “additional roll forward” messages appear in the SQL Server Error Log or Windows Event Viewer under Event ID 4303.

Alternative or Verification Steps

  • Verify success by checking the database state with SELECT name, state_desc FROM sys.databases WHERE name = 'YourDB'; it should report ONLINE.
  • If a required log backup is permanently lost, your only alternative is to restore to the last consistent point using WITH STOPAT set just before the gap, accepting data loss up to that LSN.