How to fix Error 5295 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 5295 – DBCC UPDATEUSAGE Cannot Acquire Lock on ‘sysallocunits’

Why This Error Happens

Error 5295 occurs when DBCC UPDATEUSAGE attempts to acquire an exclusive internal lock on the sysallocunits system table, but another session, transaction, or concurrent DBCC/maintenance process is already holding a conflicting lock. This is common when the command runs alongside active index rebuilds, auto-stats updates, or another instance of DBCC UPDATEUSAGE/CHECKDB targeting the same database. Lock contention can also be prolonged by long-running transactions, blocking chains, or insufficient lock timeout settings in SQL Server 2025.

Step-by-Step Resolution Guide

Step 1: Identify Blocking Sessions

  • Run sp_who2 or query sys.dm_exec_requests and sys.dm_tran_locks to find sessions blocking access to sysallocunits.
  • Look specifically for SPIDs with wait_type containing LCK_M_* and resource_type = 'OBJECT'.
  • Command example:
  SELECT request_session_id, resource_type, resource_description, request_mode, request_status
  FROM sys.dm_tran_locks
  WHERE resource_database_id = DB_ID('YourDatabaseName');

Step 2: Terminate or Wait Out Conflicting Processes

  • If a long-running index maintenance job (e.g., ALTER INDEX REBUILD) is active, allow it to complete or reschedule DBCC UPDATEUSAGE outside that window.
  • If safe to do so, kill the blocking SPID using KILL <session_id>; after confirming it is not a critical production transaction.
  • Avoid running DBCC UPDATEUSAGE during peak maintenance plan execution windows.

Step 3: Run DBCC UPDATEUSAGE in Single-User or Isolated Mode

  • Use ALTER DATABASE [YourDatabaseName] SET SINGLE_USER WITH ROLLBACK IMMEDIATE; to eliminate contention (only during maintenance windows).
  • Execute the command:
  DBCC UPDATEUSAGE (YourDatabaseName) WITH NO_INFOMSGS;
  • Revert back using ALTER DATABASE [YourDatabaseName] SET MULTI_USER; once completed.

Step 4: Increase Lock Timeout and Retry

  • Set a higher lock timeout value to allow the operation more time to acquire the lock gracefully:
  SET LOCK_TIMEOUT 60000; -- 60 seconds
  • Re-run DBCC UPDATEUSAGE immediately after setting this session-level parameter.

Step 5: Verify SQL Server 2025 Service Health

  • Check Windows Server 2025 Event Viewer under Applications and Services Logs > Microsoft > SQL Server for related tempdb or allocation errors.
  • Restart the SQL Server service via SQL Server Configuration Manager if lock contention persists due to an orphaned internal transaction.

Alternative or Verification Steps

  • After re-running DBCC UPDATEUSAGE, confirm success by checking the output for “DBCC execution completed” with no error messages, and cross-verify row/page counts using sp_spaceused.
  • If the issue persists, run DBCC CHECKDB first to rule out underlying corruption, as persistent allocation locks can sometimes indicate corrupted sysallocunits metadata requiring a restore from backup.