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 September 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 agent is available from Microsoft Update, Microsoft Update Catalog, and Microsoft Download Center. 

Notes:

  • If the Azure File Sync agent is not currently installed on a server, use the agent installation package on the Microsoft Download Center. The agent installation package on Microsoft Update and Microsoft Update Catalog is intended for agent upgrades only.
  • To update existing agent installations, run AfsUpdater.exe (located in the agent installation directory) or download and install the update from Microsoft Update or Microsoft Update Catalog.

Microsoft Update

To obtain and install from Microsoft Update, follow these steps on a server that has Azure File Sync agent installed: 

  1. Click Start, and then click Settings.
  2. In Settings, click Update & security.
  3. In the Windows Update window, click Check online for updates from Microsoft Update.
  4. Verify the Azure File Sync agent update is listed and then click Install now.

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 KB5072939.log

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

msiexec.exe /p StorageSyncAgent_WS2016_KB5072939.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l*v KB5072939.log

Microsoft Download Center

Go to the Microsoft Download Center to manually download the agent installation package for new agent installations. 

How to perform a silent installation for a new agent installation

To perform a silent installation for a new agent installation that uses the default settings, run the following command at an elevated command prompt: 

msiexec /i packagename.msi /qb /l*v AFSv23.1Installation.log 

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

msiexec /i StorageSyncAgent_WS2016.msi /qb /l*v AFSv23.1Installation.log 

Notes:

Use the /qb switch to display restart prompts (if required), agent update, and server registration screens. To suppress the screens and automatically restart the server (if required), use the /qn switch.

To perform a silent installation with custom settings, see How to install the Azure File Sync agent silently.