Troubleshooting Guide: SQL Server Error 4318 — “File Has Been Rolled Forward to LSN”

Why This Error Happens

Error 4318 occurs when SQL Server attempts to apply a transaction log backup that is out of sequence with the database’s current recovery state, meaning the database has already been rolled forward past the point where this specific log file begins. This typically happens when a log backup is restored out of order, a backup in the restore chain is skipped or missing, or the LSN (Log Sequence Number) chain has been broken due to a manual log truncation or a mismatched backup set. In essence, SQL Server is detecting a gap or overlap in the continuity required to replay transaction logs correctly.

Step-by-Step Resolution Guide

Step 1: Verify the Restore Sequence and LSN Chain

• Open SQL Server Management Studio (SSMS) or run a query using RESTORE HEADERONLY against each backup file to inspect FirstLSN, LastLSN, and CheckpointLSN values.
• Confirm backups are being restored strictly in chronological order: Full → Differential (if any) → Transaction Logs in sequence.
• Use the following query to check the current recovery LSN of the target database:

  SELECT name, redo_start_lsn, differential_base_lsn 
  FROM sys.master_files 
  WHERE database_id = DB_ID('YourDatabaseName');

Step 2: Restart the Restore Chain from the Last Valid Full Backup

• Drop or restore the database WITH REPLACE using the most recent full backup to reset the baseline LSN.
• Example command:

  RESTORE DATABASE YourDatabaseName 
  FROM DISK = 'C:\Backups\YourDatabase_Full.bak' 
  WITH NORECOVERY, REPLACE;

• Reapply differential and log backups strictly in the correct order without skipping any file in the sequence.

Step 3: Identify and Exclude the Mismatched or Duplicate Log File

• Check the specific log backup referenced in the error message (the file path shown in %ls) and compare its FirstLSN against the database’s current redo_start_lsn.
• If the log file’s starting LSN is lower than the current rolled-forward LSN, it is redundant — skip it and move to the next sequential log file in the chain.
• Locate backup history in msdb.dbo.backupset to rebuild an accurate timeline:

  SELECT backup_start_date, first_lsn, last_lsn, type 
  FROM msdb.dbo.backupset 
  WHERE database_name = 'YourDatabaseName' 
  ORDER BY backup_start_date;

Step 4: Validate Backup Integrity and Storage Path

• On Windows Server 2025 / Windows 11, confirm the backup files haven’t been corrupted or truncated during transfer (check file size and CHECKSUM if enabled during backup).
• Verify the backup storage path (e.g., D:\SQLBackups\TransactionLogs\) is accessible and not subject to permission issues or antivirus interference that could lock/alter files mid-restore.
• Run RESTORE VERIFYONLY FROM DISK = 'PathToFile.trn' to confirm backup file integrity before reattempting the restore.

Step 5: Reapply Logs Using STOPAT or NORECOVERY Correctly

• Ensure every restore command except the final one uses WITH NORECOVERY to keep the database in a restoring state.
• Only the last transaction log in the sequence should use WITH RECOVERY to bring the database online.
• Example:

  RESTORE LOG YourDatabaseName 
  FROM DISK = 'D:\SQLBackups\Log_02.trn' 
  WITH NORECOVERY;

Alternative or Verification Steps

• After completing the restore chain, run DBCC CHECKDB('YourDatabaseName') to confirm database consistency and that no corruption resulted from the interrupted restore sequence.
• If the LSN chain is irreparably broken (e.g., a required log backup is permanently lost), the only alternative is to restore from the last known good full/differential backup and accept data loss up to that point, then re-establish a new log backup chain going forward.