Troubleshooting Guide: SQL Server Error 4333 — “Database Cannot Be Recovered Because the Log Was Not Restored”

Why This Error Happens

Error 4333 occurs when SQL Server attempts to bring a database online but detects that the required transaction log restore sequence was never completed, leaving the database in a state where it cannot reconcile data file LSNs (Log Sequence Numbers) with the log file. This is most commonly caused by an interrupted restore chain (e.g., restoring a full backup without applying subsequent differential or log backups before issuing RESTORE DATABASE ... WITH RECOVERY), a missing or corrupted .ldf file, or a mismatched backup sequence where files were restored out of order. It can also occur if the log file was manually deleted or moved while the database was in a RESTORING state.

Step-by-Step Resolution Guide

Step 1: Verify the Current Restore State of the Database

• Run the following query to check if the database is still in NORECOVERY or RESTORING mode:

  SELECT name, state_desc FROM sys.databases WHERE name = 'YourDatabaseName';

• If state_desc shows RESTORING, the database is mid-sequence and still expects additional log files.
• Check the SQL Server Error Log (located at C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG) for the exact point of failure in the restore chain.

Step 2: Reapply the Correct Backup Restore Sequence

• Identify the last successful full backup and all subsequent differential/log backups using:

  RESTORE HEADERONLY FROM DISK = 'D:\Backups\YourDatabase_Full.bak';

• Restore the full backup with NORECOVERY:

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

• Apply all transaction log backups in chronological order (do not skip any .trn files), ending with the final log file using WITH RECOVERY:

  RESTORE LOG YourDatabaseName 
  FROM DISK = 'D:\Backups\YourDatabase_Log1.trn' 
  WITH NORECOVERY;

  RESTORE LOG YourDatabaseName 
  FROM DISK = 'D:\Backups\YourDatabase_Log_Final.trn' 
  WITH RECOVERY;

Step 3: Check File Permissions and Path Integrity on Windows Server 2025

• Navigate to the SQL Server data directory (typically C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA\) and confirm the .ldf file exists and is not flagged as Read-Only.
• Ensure the SQL Server service account (visible in SQL Server Configuration Manager) has Full Control NTFS permissions on both the DATA and backup folders.
• If the log file is missing or corrupted, and you have no valid log backup, you may need to force the database into emergency mode as a last resort:

  ALTER DATABASE YourDatabaseName SET EMERGENCY;
  DBCC CHECKDB(YourDatabaseName, REPAIR_ALLOW_DATA_LOSS);

Step 4: Rebuild the Transaction Log (If No Backups Are Recoverable)

• If Step 2 and Step 3 fail due to permanently lost log backups, detach the database and attempt a log rebuild:

  ALTER DATABASE YourDatabaseName REBUILD LOG ON 
  (NAME=YourDatabaseName_log, FILENAME='D:\Data\YourDatabaseName_log.ldf');

• Immediately run DBCC CHECKDB afterward, as this action breaks the transaction log chain and may result in data loss.

Alternative or Verification Steps

• After recovery, confirm the database is online and accessible by running SELECT state_desc FROM sys.databases WHERE name = 'YourDatabaseName'; — it should return ONLINE.
• If the issue persists, use SQL Server Management Studio (SSMS) to right-click the database, select Tasks > Restore > Database, and use the GUI timeline feature to visually verify no backup files are missing from the restore plan before retrying.