How to fix Error 5545 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5545 — FILESTREAM Kernel Driver Connection

Why This Error Happens

Error 5545 is not an actual error — it is an informational message logged by SQL Server during startup to confirm that the FILESTREAM feature has successfully connected to its kernel-mode driver (RsFx). This message typically appears when FILESTREAM is enabled at the instance level and the SQL Server service initializes the driver that handles streaming BLOB data between the database engine and the NTFS/ReFS file system. It gets flagged or reported as a concern only because administrators sometimes mistake it for a warning when reviewing the SQL Server Error Log or Windows Event Viewer, when in reality it confirms correct FILESTREAM initialization.

Step-by-Step Resolution Guide

Step 1: Confirm This Is Informational Only

  • Open SQL Server Management Studio (SSMS) and navigate to Management > SQL Server Logs.
  • Locate the entry matching: FILESTREAM: effective level = 3, ... connected to kernel driver %ls.
  • Confirm the message severity is Informational (not Error/Warning) — no corrective action is required if FILESTREAM features are working as expected.

Step 2: Verify FILESTREAM Configuration Is Intentional

  • Open SQL Server Configuration Manager on Windows Server 2025 / Windows 11.
  • Right-click your instance (e.g., SQL Server (MSSQLSERVER)) → Properties → FILESTREAM tab.
  • Ensure “Enable FILESTREAM for Transact-SQL access” is checked only if your applications actually require it.
  • If FILESTREAM is not needed, uncheck all FILESTREAM options and restart the SQL Server service to suppress this message going forward.

Step 3: Validate the Driver and Service Dependencies

  • Open Device Manager → View > Show hidden devices → expand Non-Plug and Play Drivers.
  • Confirm RsFx0101 (or current version) driver is listed and shows This device is working properly.
  • From an elevated PowerShell prompt, run:
  Get-Service RsFx01010 | Select-Object Status, StartType
  • Ensure the service Status is Running and StartType is Automatic.

Step 4: Check File System and Share Permissions (If Using FILESTREAM Storage)

  • Navigate to your configured FILESTREAM share path, typically found via:
  SELECT * FROM sys.master_files WHERE type_desc = 'FILESTREAM';
  • Confirm the SQL Server service account has Modify permissions on the FILESTREAM data container folder.
  • Validate the Windows file share (if used) has matching NTFS and share-level permissions.

Alternative or Verification Steps

  • Restart the SQL Server instance and re-check SQL Server Logs; the 5545 message reappearing at startup with Informational severity confirms normal, expected behavior.
  • If FILESTREAM is not used by any application or database, disable it entirely via Configuration Manager and in sp_configure 'filestream access level', 0; followed by RECONFIGURE; to eliminate the message permanently.