How to fix Error 5574 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: Error 5574 – Database Mirroring Incompatible with FILESTREAM/MEMORYOPTIMIZEDDATA

Why This Error Happens

Error 5574 occurs because SQL Server 2025 does not support combining legacy Database Mirroring with FILESTREAM or MEMORYOPTIMIZEDDATA (In-Memory OLTP) features on the same database. This is a hard architectural restriction, not a configuration bug, since mirroring cannot synchronize the filesystem-based FILESTREAM data or the checkpoint files used by memory-optimized filegroups between the principal and mirror servers. Attempting to enable mirroring on a database that already contains a FILESTREAM filegroup or a MEMORYOPTIMIZEDDATA filegroup will always trigger this error.

Step-by-Step Resolution Guide

Step 1: Confirm the Conflicting Feature

  • Run the following query to check for FILESTREAM or memory-optimized filegroups on the target database:
SELECT name, type_desc FROM sys.filegroups WHERE type_desc IN ('FILESTREAM_DATA_FILEGROUP', 'MEMORY_OPTIMIZED_DATA_FILEGROUP');
  • Identify whether the conflict is caused by FILESTREAM, In-Memory OLTP, or both.

Step 2: Choose an Alternative High-Availability Technology

  • Since Database Mirroring was deprecated starting in SQL Server 2012 and is fully removed from newer default workflows in SQL Server 2025, migrate to Always On Availability Groups instead.
  • Open SQL Server Configuration Manager on Windows Server 2025, enable the Always On Availability Groups service under the SQL Server service properties (High Availability tab), and restart the SQL Server service.
  • Always On Availability Groups natively support both FILESTREAM and MEMORYOPTIMIZEDDATA, unlike legacy mirroring.

Step 3: Remove the Conflicting Filegroup (If Mirroring Must Be Retained)

  • If Availability Groups are not an option and mirroring is mandatory, remove the FILESTREAM or memory-optimized filegroup from the database:
ALTER DATABASE [YourDB] REMOVE FILE [FileStreamGroupName];
ALTER DATABASE [YourDB] REMOVE FILEGROUP [FileStreamGroupName];
  • Ensure no tables reference FILESTREAM columns or memory-optimized tables before dropping the filegroup, as this operation is irreversible without a backup.

Step 4: Reconfigure Mirroring

  • Once the conflicting filegroup is removed, re-attempt to enable mirroring via SQL Server Management Studio (SSMS) under Database Properties > Mirroring, or via T-SQL:
ALTER DATABASE [YourDB] SET PARTNER = 'TCP://MirrorServer:5022';
  • Confirm the mirroring session establishes without throwing Error 5574.

Step 5: Validate Server-Level Compatibility

  • Check that both the principal and mirror instances are running the same SQL Server 2025 build and edition, since mismatched editions can cause secondary configuration failures after resolving the filegroup conflict.
  • Use SELECT @@VERSION; on both instances to confirm parity.

Alternative or Verification Steps

  • Verify the fix by querying sys.database_mirroring on the principal database — a non-null mirroring_state_desc value of SYNCHRONIZED confirms mirroring is active without errors.
  • If removing FILESTREAM/In-Memory OLTP is not feasible, use Log Shipping or Always On Availability Groups as a direct replacement, since both fully support these storage features in SQL Server 2025.