Azure File Sync Agent V23.1 - September 2026

This article describes the improvements and issues that are fixed in the Azure File Sync Agent v23.1 release that is dated August 2026. Additionally, this article contains installation instructions for this release.

Improvements and issues that are fixed

Recommended alerts You can now enable a set of pre-configured recommended alerts for your Storage Sync Service to monitor sync health, server connectivity, storage availability, and agent expiration. See Monitor Azure File Sync.

Miscellaneous reliability and telemetry improvements for cloud tiering and sync

  • Improved the performance of directory enumeration on the server, delivering roughly a 25% speedup when scanning large directory structures.
  • Local changes on the server are now detected and synced promptly, even while a large enumeration is in progress.
  • Addressed corner-case conditions that could leave stale entries in the sync database, and improved handling of files that are briefly in use during sync, for more consistent sync behavior.

More information about the Azure File Sync Agent v23.1 release

  • This release is available for Windows Server 2016, Windows Server 2019, Windows Server 2022 and Windows Server 2025 installations.

  • The agent version for this release is 23.1.0.0.

  • The Azure File Sync agent requires .NET Framework 4.7.2 or later. Windows Server 2019 and later include .NET Framework 4.7.2 by default. For Windows Server 2016, verify that .NET Framework 4.7.2 or later is installed before installing Azure File Sync.

  • The following updates must be installed on the Windows Server:

Cumulative updates are released monthly. To deploy the latest one, users can either use Windows Update or manually download it from the Microsoft Update Catalog. If installing manually, they should review the associated KB article to ensure all prerequisites are met.

Note: If the Windows Updates are not installed prior to installing the Azure File Sync agent, the Storage Sync Agent service (FileSyncSvc) will fail to start. To learn more, see the Azure File Sync troubleshooting documentation.

How to obtain and install the Azure File Sync Agent

The Azure File Sync v23.1 release is currently being flighted to servers which are configured to automatically update when a new version becomes available. Once fighting completes, this update will be available on Microsoft Update and Microsoft Download Center. Flighting means the release is offered to a limited number of servers first and expands to more servers gradually. It may not be offered to your server right away even if it’s configured to automatically update when a new version becomes available. To immediately install the Azure File Sync v23.1 release, manually download the update from the Microsoft Update Catalog.

To learn more about Azure File Sync agent auto-update, see Automatic Agent Lifecycle

To obtain and install this update, configure your Azure File Sync agent to automatically update when a new version becomes available or manually download the update from the Microsoft Update Catalog.

Configure your Azure File Sync agent to automatically update when a new version becomes available

Agent installation During the Azure File Sync agent installation, select the “Automatically update when a new version becomes available” setting. 

Post-agent installation If the agent is already installed, run the following PowerShell commands to configure auto-update:

Import-Module "C:\Program Files\Azure\StorageSyncAgent\StorageSync.Management.ServerCmdlets.dll" 
Set-StorageSyncAgentAutoUpdate -PolicyMode InstallLatest -Day <day> -Hour <hour> 

Manually download and install the Azure File Sync agent update from the Microsoft Update Catalog

Go to the following website to manually download this update from the Microsoft Update Catalog: Azure File Sync Agent v23.1 release - September 2026 (KB5072939)

To manually install the update package, extract the cab file and run the following command from an elevated command prompt:

*msiexec.exe /p packagename.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l\*v KB*5072939*.log*

For example, to install the Azure File Sync agent update for Server 2016, run the following command:

*msiexec.exe /p StorageSyncAgent\_WS2016\_KB*5072939*.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l\*v KB*5072939*.log*