How to fix Error 5804 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5804 — Character Set / Configuration Mismatch

Why This Error Happens

Error 5804 typically occurs when SQL Server 2025 detects a mismatch between the character set configuration stored in the instance’s registry settings and the actual collation or locale configured during setup. This often happens after an incomplete installation, a corrupted master database resource file, or when the server’s regional/locale settings on Windows Server 2025 or Windows 11 were changed after SQL Server was installed. In some cases, this is also triggered by a damaged Resource.ide or Resource.mdf file not matching the installed code page.

Step-by-Step Resolution Guide

Step 1: Verify the Server Collation and Locale Settings

  • Open SQL Server Management Studio (SSMS) and run: SELECT SERVERPROPERTY('Collation');
  • Compare the returned collation with the OS locale under Control Panel > Region > Administrative > Language for non-Unicode programs.
  • Note any mismatch between the SQL Server collation code page and the Windows system locale.

Step 2: Rebuild the Master Database with Correct Collation

  • Open Command Prompt as Administrator and navigate to the SQL Server installation binn directory, typically: C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Binn
  • Run the setup rebuild command:
  setup.exe /QUIET /ACTION=REBUILDDATABASE /INSTANCENAME=MSSQLSERVER /SQLSYSADMINACCOUNTS=BUILTIN\Administrators /SAPWD=<StrongPassword> /SQLCOLLATION=SQL_Latin1_General_CP1_CI_AS
  • Replace SQL_Latin1_General_CP1_CI_AS with the collation matching your application’s required character set.

Step 3: Check and Restore the Resource Database Files

  • Navigate to: C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Binn\Templates
  • Confirm Resource.mdf and Resource.ldf exist and are not zero-byte or corrupted.
  • If corrupted, restore these files from the original installation media or a verified backup, then restart the SQL Server (MSSQLSERVER) service via services.msc.

Step 4: Restart SQL Server Services and Validate Configuration

  • Open services.msc on Windows Server 2025/Windows 11.
  • Restart SQL Server (MSSQLSERVER) and SQL Server Agent services.
  • Re-run: SELECT SERVERPROPERTY('Collation'); to confirm the setting now matches the expected character set.

Alternative or Verification Steps

  • Run DBCC CHECKDB('master') to confirm no further corruption exists after the rebuild, and test data retrieval queries that previously failed due to Error 5804.
  • If the issue persists, perform a full uninstall/reinstall of the SQL Server 2025 instance, explicitly specifying the correct /SQLCOLLATION parameter during setup to prevent recurrence.