How to fix Error 5529 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5529 – FILESTREAM File Removal Failure in Availability Groups

Why This Error Happens

This error occurs because SQL Server 2025 enforces synchronization guarantees for FILESTREAM data in Always On Availability Groups, preventing a DROP FILE operation until all secondary replicas confirm they have hardened (written to disk) the corresponding FILESTREAM data. If one or more secondary replicas are lagging, offline, disconnected, or stuck in a non-synchronized state, the primary database cannot verify that the file removal is safe to propagate. This is typically caused by slow network throughput between replicas, a secondary replica in a RESOLVING or NOT SYNCHRONIZING state, or large unprocessed FILESTREAM data in the log queue.

Step-by-Step Resolution Guide

Step 1: Verify the Availability Group Health State

  • Open SQL Server Management Studio (SSMS) and connect to the primary replica.
  • Run SELECT * FROM sys.dm_hadr_availability_replica_states; to check the synchronization_state_desc column for all replicas.
  • Confirm every secondary replica shows SYNCHRONIZED or SYNCHRONIZING and not NOT SYNCHRONIZING.

Step 2: Check FILESTREAM Hardening Progress on Secondary Replicas

  • On each secondary replica, run SELECT * FROM sys.dm_io_pending_io_requests; to identify pending I/O on the FILESTREAM filegroup volume.
  • Inspect the physical FILESTREAM container path (commonly D:\SQLData\FileStreamData\) to ensure the Windows Server 2025 storage subsystem is not reporting disk latency via Performance Monitor (Avg. Disk sec/Write counter).
  • Resolve any underlying storage bottlenecks, such as upgrading from spinning disk to NVMe/SSD-backed storage pools.

Step 3: Resynchronize the Lagging Secondary Replica

  • In SSMS, right-click the Availability Group in Object Explorer and select Show Dashboard to pinpoint which replica is behind.
  • If a replica is stalled, manually remove and re-add it using:
ALTER AVAILABILITY GROUP [YourAGName] REMOVE REPLICA ON N'SecondaryReplicaName';
  • Re-add the replica through the Add Replica Wizard, ensuring the Automatic Seeding option is enabled for faster FILESTREAM data transfer.

Step 4: Retry the DROP FILE Operation

  • Once all replicas report SYNCHRONIZED, re-run the original command, for example:
ALTER DATABASE [YourDatabase] REMOVE FILE [FileStreamLogicalName];
  • Monitor the SQL Server Error Log (C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG) for confirmation that the file was dropped without error 5529 recurring.

Alternative or Verification Steps

  • Verify success by querying sys.master_files on both the primary and all secondary replicas to confirm the FILESTREAM file entry no longer exists on any node.
  • If the issue persists under heavy load, temporarily fail over the Availability Group to a healthy secondary, perform the DROP FILE operation while that node acts as primary, then fail back once replication stabilizes.