How to fix Error 5575 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5575

Why This Error Happens

Error 5575 typically occurs when SQL Server 2025 encounters a low-level I/O or file system operation failure while interacting with the Windows Server 2025 / Windows 11 storage subsystem. This is most commonly caused by corrupted database files, insufficient NTFS permissions on the data/log directories, or a failure returned by the underlying Windows API (reflected in the HRESULT) due to disk corruption, antivirus interference, or a locked file handle. In some cases, this also surfaces when FILESTREAM or memory-mapped file operations fail because the service account lacks the necessary privileges.

Step-by-Step Resolution Guide

Step 1: Identify the Exact File and HRESULT Code

  • Open the SQL Server Error Log via SSMS or C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG.
  • Locate the full error string to extract the file path (%hs) and HRESULT value (%ls).
  • Cross-reference the HRESULT using certutil -error <HRESULTCode> in an elevated Command Prompt to decode the Windows-level meaning (e.g., access denied, disk full, file not found).

Step 2: Verify File System Permissions and Integrity

  • Right-click the affected data/log file folder (commonly C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\DATA) and check Properties > Security.
  • Ensure the SQL Server service account (e.g., NT Service\MSSQLSERVER) has Full Control over the DATA, LOG, and Backup directories.
  • Run chkdsk C: /f /r from an elevated prompt and schedule a restart if the volume hosting the database files is suspected of corruption.

Step 3: Exclude SQL Server Directories from Antivirus/Defender Scanning

  • Open Windows Security > Virus & threat protection > Manage settings > Add or remove exclusions.
  • Add exclusions for the .mdf, .ndf, .ldf file paths and the sqlservr.exe process.
  • Restart the SQL Server service via services.msc or net stop MSSQLSERVER && net start MSSQLSERVER.

Step 4: Run Database Consistency Checks

  • Open a query window in SSMS and execute DBCC CHECKDB('YourDatabaseName') WITH NO_INFOMSGS, ALL_ERRORMSGS;.
  • Review the output for allocation or structural errors tied to the file mentioned in the original error message.
  • If corruption is confirmed, restore from the last known good backup rather than attempting an in-place repair on production data.

Alternative or Verification Steps

  • After applying fixes, re-run the operation that originally triggered Error 5575 and monitor the ERRORLOG in real time using Get-Content -Path "ERRORLOG" -Wait in PowerShell.
  • If the error persists, detach the database, move the files to a different (non-corrupted) volume, and re-attach using CREATE DATABASE ... FOR ATTACH to rule out underlying disk hardware issues.