How to fix Error 5177 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: SQL Server Error 5177 – Sector Size Check Failure

Why This Error Happens

This error occurs when SQL Server 2025 attempts to verify the physical sector size of a database file but cannot complete the check because the file resides on a volume that doesn’t support the required NTFS-level API calls (such as network shares, ReFS volumes without proper configuration, or compressed/encrypted drives). It can also happen if the underlying disk uses a non-standard sector size (like 4Kn drives) that conflicts with SQL Server’s I/O alignment requirements. Additionally, corrupted file system metadata or insufficient permissions on the storage volume can prevent the GetDiskFreeSpace or FSCTL_QUERY_DISK_SECTOR_SIZE API calls from returning valid data.

Step-by-Step Resolution Guide

Step 1: Verify the File Location and Volume Type

  • Confirm the database file (.mdf, .ldf, or .ndf) is not stored on a network share (UNC path), USB drive, or mapped network drive.
  • Run fsutil fsinfo volumeinfo C: in an elevated Command Prompt to confirm the volume is formatted as NTFS, not ReFS, FAT32, or exFAT.
  • If the file is on a non-NTFS volume, plan to migrate it to a local NTFS-formatted disk.

Step 2: Move the Database File to a Supported Local NTFS Volume

  • Stop the SQL Server service via services.msc or run NET STOP MSSQLSERVER in an elevated prompt.
  • Physically copy the affected .mdf/.ldf file to a local NTFS path, such as C:\SQLData\.
  • Update the file path reference using ALTER DATABASE [YourDB] MODIFY FILE (NAME = YourLogicalFileName, FILENAME = 'C:\SQLData\YourFile.mdf').
  • Restart the SQL Server service with NET START MSSQLSERVER.

Step 3: Check Disk Sector Size Compatibility

  • Run fsutil fsinfo sectorinfo C:\SQLData to inspect the physical and logical sector size of the target drive.
  • Ensure the drive does not report an unsupported Advanced Format (4Kn) configuration without proper driver support in Windows Server 2025.
  • If using 4Kn drives, confirm you are running the latest storage controller and SQL Server 2025 cumulative update, as early builds have had compatibility issues with native 4K sector reporting.

Step 4: Validate Permissions on the Storage Volume

  • Right-click the target folder (e.g., C:\SQLData), select Properties > Security, and confirm the SQL Server service account (e.g., NT Service\MSSQLSERVER) has Full Control.
  • Run icacls C:\SQLData from an elevated Command Prompt to audit current permissions.
  • Grant missing permissions using icacls C:\SQLData /grant "NT SERVICE\MSSQLSERVER":(OI)(CI)F.

Step 5: Rule Out File System Corruption

  • Run chkdsk C: /f /r and schedule a restart if prompted, to repair any underlying NTFS structure issues.
  • Re-attempt the database attach or file creation operation once the check completes.

Alternative or Verification Steps

  • After moving the file, attempt to attach or restore the database again using sp_attach_db or RESTORE DATABASE, and confirm Error 5177 no longer appears in the SQL Server Error Log.
  • If the error persists on a local NTFS drive, test with a brand-new, simple database file created directly via CREATE DATABASE TestDB ON (NAME = TestDB, FILENAME = 'C:\SQLData\TestDB.mdf') to isolate whether the issue is file-specific or environment-wide (driver/storage controller related).