How to fix Error 7452 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 7452 — MWC Token Cache Initialization Failure

Why This Error Happens

Error 7452 occurs when SQL Server 2025 fails to initialize the Memory Workload Controller (MWC) Token Cache during the startup or runtime lock acquisition phase, typically due to insufficient memory reservation or a conflict in the lock mode specified. This often stems from restrictive memory limits configured in sp_configure (such as ‘min server memory’ or ‘max server memory’) that prevent the token cache from allocating the required internal structures. Additionally, corrupted resource governor pools or stale authentication tokens tied to the Windows Server 2025 security subsystem can trigger this lock contention error.

Step-by-Step Resolution Guide

Step 1: Verify SQL Server Memory Configuration

  • Open SQL Server Management Studio (SSMS) and connect to the instance via a Dedicated Administrator Connection (DAC) if the service is unresponsive.
  • Run EXEC sp_configure 'show advanced options', 1; RECONFIGURE; followed by EXEC sp_configure; to check current memory allocations.
  • Ensure ‘max server memory (MB)’ is not set lower than the minimum required for the MWC cache (recommended baseline: 4096 MB for 2025 builds).

Step 2: Clear Corrupted Token Cache Files

  • Stop the SQL Server service via services.msc or by running NET STOP MSSQLSERVER in an elevated Command Prompt.
  • Navigate to the instance’s data directory, typically located at C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA\.
  • Delete or rename temporary cache files with the .mwc or .tok extension found in the Temp subfolder.
  • Restart the service using NET START MSSQLSERVER.

Step 3: Check Windows Security and Lock Permissions

  • Open the Local Security Policy editor (secpol.msc) on Windows Server 2025 or Windows 11.
  • Verify that the SQL Server service account has the “Lock pages in memory” user right assigned under Local Policies > User Rights Assignment.
  • Confirm there are no Group Policy Object (GPO) conflicts overriding local token lock settings by running gpresult /h report.html and reviewing applied policies.

Step 4: Rebuild the Resource Governor Pool

  • Execute ALTER RESOURCE GOVERNOR RESET STATISTICS; in a new query window to flush the existing lock states.
  • Run ALTER RESOURCE GOVERNOR RECONFIGURE; to force the Resource Governor to rebuild the token cache from scratch.
  • Monitor the SQL Server Error Log (ERRORLOG file in the LOG folder) for confirmation that the MWC initialized successfully on the next restart.

Alternative or Verification Steps

  • To verify the fix, check the SQL Server Error Log for the absence of Error 7452 and look for the informational message “MWC Token Cache initialized successfully” following a service restart.
  • If the error persists, consider running SQL Server Setup in “Repair” mode from the Installation Center to restore corrupted system binaries associated with the Resource Governor feature.