Update rollup for Azure File Sync Agent: December 2018

Applies to: Azure


This article describes the improvements and issues that are fixed in the update for the Azure File Sync Agent that's dated December 2018. Additionally, this article contains installation instructions for this release.

Improvements and issues that are fixed

  • A Stop error 0x3B or Stop error 0x1E may occur when a VSS snapshot is created.
  • The server may become unresponsive because of a cloud-tiering memory leak.
  • Agent installation fails with the following error:
  • The Storage Sync Agent (FileSyncSvc) service may crash when memory usage is high.
  • Miscellaneous reliability improvements for cloud tiering and sync.

Note Update rollups for Azure File Sync Agent are cumulative. This update includes all the improvements and fixes that were included in the previous cumulative update.

More information about this update rollup

  • This update is available for Windows Server 2012 R2, Windows Server 2016, and Windows Server 2019 installations that have Azure File Sync agent version or a later version installed.
  • The agent version of this update rollup is
  • A restart may be required if certain files are being used during the update rollup installation.

How to get and install this update rollup for the Azure File Sync Agent

Update rollups for the Azure File Sync Agent are available from Microsoft Update and by manual download.


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

Microsoft Update

To get and install this update rollup from Microsoft Update, follow these steps on a server that has Azure File Sync Agent installed:

Windows Server 2016

  1. Select Start, and then select Settings.
  2. In Settings, select Update & security.
  3. In the Windows Update window, select Check online for updates from Microsoft Update.
  4. Verify that the update rollup is listed, and then select Install now.

Windows Server 2012 R2

  1. Select Start, and then select Control Panel.
  2. In Control Panel, double-click Windows Update.
  3. In the Windows Update window, select Check for updates.
  4. Select Important updates are available.
  5. Verify that the update rollup is selected, and then click Install.

Microsoft Update Catalog

Go to the following website to manually download this update rollup package from the Microsoft Update Catalog:

 Update Rollup for Azure File Sync Agent: December 2018 (KB4459988)

To manually install the update rollup package, run the following command from an elevated command prompt:

msiexec.exe /p packagename.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l*vx storagesyncagentupdate.log

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

msiexec.exe /p StorageSyncAgent_WS2016_KB4459988.msp REINSTALLMODE=OMUS REINSTALL=StorageSyncAgent,StorageSyncAgentAzureFileSync,StorageSyncAgentGuardFilter,StorageSyncAgentUpdater /qb /l*vx storagesyncagentupdate.log

New agent installation

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

Note To perform a silent installation for new agent installations, following the steps documented in KB 4459986.


Learn about the standard terminology that Microsoft uses to describe software updates.