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This update for Azure Stack version 1903 includes reliability improvements. No new features are being introduced in this update. Important changes include the following:

  • Fix time out issue during stop-deallocate of IaaS VMs with multiple large managed disks.

  • Increase VM uptime when a system is updating.

  • Fix issues with resource exhaustion when the system is running at scale improving overall system stability.

  • Update to Windows Defender engine to address issues with storage availability.  


  • IaaS VM with multiple large managed disks: During stop-deallocate, the operation fails due to time out.

  • VM uptime during system updates: Azure Stack updates perform a rolling update of the scale-unit by draining one node at a time and updating it. During node drain, the goal is to evacuate a node with no perceived downtime to the VM. However, if the network is under heavy load, VMs may incur a brownout or a blackout.

  • Resource exhaustion: When a system is running at scale, internal processes may exhaust platform resources resulting in failed operations in the portal.

  • Windows Defender: Issues in the Windows Defender engine impact the availability of storage.


  • IaaS VM with multiple large managed disks: Missing information in CRP impacts the stop-deallocate operation.

  • VM uptime during system updates: Number of concurrent VMs evacuate and bandwidth consumed is too high.

  • Resource exhaustion: Sub-optimal Throttling of resource allocation for process execution.

  • Windows Defender: Stability issues identified in the Windows Defender engine in this release.


  • IaaS VM with multiple large managed disks: Fix in CRP to address the time out.

  • VM uptime during system updates: Reduce the number of VMs evacuated concurrently and place a cap on bandwidth consumed.

  • Resource exhaustion: Optimize resource throttling.

  • Windows Defender: Update Windows Defender engine version. 

Hotfix information

To apply this hotfix, you must have version 1.1903.0.35 installed.

Important: As outlined in the Release Notes for the 1903 update, be sure to follow the instructions in the Prerequisites section on running Test-AzureStack (with specified parameters) and resolve any operational issues found, including all warnings and failures. Also review active alerts and resolve any that require action.

File information

How to get this update

Download the following files. As soon as the files have been downloaded, follow the instructions on the Apply updates in Azure Stack page on the Microsoft Learn website to apply this update to Azure Stack.

Download the hotfix .zip file now.

Download the hotfix .xml file now.

More information

Azure Stack update resources

Manage updates in Azure Stack overview

Apply updates in Azure Stack

Monitor updates in Azure Stack by using the privileged endpoint

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