Managing Hotpatching for Azure Arc connected Machines using APIs
Hotpatching is available as an option for Aure Arc connected Windows Server 2025 Datacenter and Standard machines. To learn more about hotpatching please review this article. Azure Arc portal provides a way for you to enroll or disenroll from hotpatching. To manage hotpatch updates, you can use Azure Update Manager (AUM) or any other patch management tool that has built the hotpatch management capability. You can also choose to use the published APIs to manage hotpatch enrollment and updates. This article provides a sample script of using the APIs to perform the different actions. Always test these scripts in your development environment and tweak to your company’s security posture. Below are the high-level management actions you may perform Enrolling/Disenrolling from hotpatch for Arc connected servers Temporarily opt-in or opt-out of without disenrolling from hotpatch Use Windows Update (WU) API to get the hotpatch update You can perform these steps today through the Azure Arc portal and AUM. However, the ability to manage updates is not limited to AUM and any update management tool can make tooling changes to facilitate hotpatch management. Hotpatch Enrollment & Disenrollment Windows Server 2025 machines that are on-premises or on non-Azure cloud, and are Azure Arc connected can enroll into hotpatch servicing. Traditionally you would have used the Azure Arc portal and manually enrolled the machine for hotpatch servicing. You can also perform the same action using APIs at your disposal. Besides enrollment, you can also disenroll from hotpatch service using these APIs. For details on these API review the specification here. Sample Scripts: Sample scripts that are used in this article may be found here: (GitHub). Examples have been added including utilizing a service principle within the scripts to assisting with automation. See sample code for Enrollment: # Enrollment workflow $subscriptionId = '' #Your subscription id $resourceGroupName = '' # your Resource Group $machineName = '' # Arc resource name $location = "" # The region where the test machine is arc enabled. $subscriptionStatus = "Enable"; # Set SubscriptionStatus to "Disable" for disenrollment $account = Connect-AzAccount -Subscription $subscriptionId $context = Set-azContext -Subscription $subscriptionId $profile = [Microsoft.Azure.Commands.Common.Authentication.Abstractions.AzureRmProfileProvider]::Instance.Profile $profileClient = [Microsoft.Azure.Commands.ResourceManager.Common.rmProfileClient]::new( $profile ) $token = $profileClient.AcquireAccessToken($context.Subscription.TenantId) $header = @{ 'Content-Type'='application/json' 'Authorization'='Bearer ' + $token.AccessToken } $uri = [System.Uri]::new( "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.HybridCompute/machines/$machineName/licenseProfiles/default?api-version=2023-10-03-preview" ) $contentType = "application/json" $data = @{ location = $location; properties = @{ productProfile = @{ productType = "WindowsServer"; productFeatures = @(@{name = "Hotpatch"; subscriptionStatus = $subscriptionStatus};) }; }; }; $json = $data | ConvertTo-Json -Depth 4; # To create a license profile resource use PUT call $response = Invoke-RestMethod -Method PUT -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; # To update a license profile resource use PATCH call #$response = Invoke-RestMethod -Method PATCH -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; $response.properties.licenseProfile Once this script is completed the hotpatch should be Enabled as shown in the Azure Portal below. When you click into the Hotpatch overview tile, it will display the Virtualization-based security (VBS) status, the license is checked for receiving monthly hotpatches, and the “Enable hotpatching” toggle is turned On. Sample code for Disenrollment # Disenrollment workflow $subscriptionId = '' #Your subscription id $resourceGroupName = '' # your Resource Group $machineName = '' # Arc resource name $location = "" # The region where the test machine is arc enabled. $subscriptionStatus = "Disable"; # Set SubscriptionStatus to "Enable" for enrollment $account = Connect-AzAccount -Subscription $subscriptionId $context = Set-azContext -Subscription $subscriptionId $profile = [Microsoft.Azure.Commands.Common.Authentication.Abstractions.AzureRmProfileProvider]::Instance.Profile $profileClient = [Microsoft.Azure.Commands.ResourceManager.Common.rmProfileClient]::new( $profile ) $token = $profileClient.AcquireAccessToken($context.Subscription.TenantId) $header = @{ 'Content-Type'='application/json' 'Authorization'='Bearer ' + $token.AccessToken } $uri = [System.Uri]::new( "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.HybridCompute/machines/$machineName/licenseProfiles/default?api-version=2023-10-03-preview" ) $contentType = "application/json" $data = @{ location = $location; properties = @{ productProfile = @{ productType = "WindowsServer"; productFeatures = @(@{name = "Hotpatch"; subscriptionStatus = $subscriptionStatus};) }; }; }; $json = $data | ConvertTo-Json -Depth 4; # To create a license profile resource use PUT call $response = Invoke-RestMethod -Method PUT -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; # To update a license profile resource use PATCH call #$response = Invoke-RestMethod -Method PATCH -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; $response.properties.licenseProfile The Hotpatch tile displays Canceled after Disenrollment. The checkbox is unchecked as well for receiving monthly hotpatches. OPT-in /OPT-out There could be scenarios where users want to temporarily opt out of Hotpatch, without disenrolling from Hotpatch service. That could be for troubleshooting or any other scenario. The option to opt-in and opt-out is available on the Azure Arc Portal, once you have enrolled in the Hotpatch service. It appears as a toggle switch for “Enable hotpatching” option. To do this programmatically review the sample code below. Opt out Sample code: # Change the following params for your test machine. $subscriptionId = '' #Your subscription id $resourceGroupName = '' # your Resource Group $machineName = '' # Arc resource name $location = "" # The region where the test machine is arc enabled. $hotpatchStatus = $false # Do you want to opt-in ($true) or Opt-Out ($false) for receiving hotpatch without changing the license to get hotpatch. $account = Connect-AzAccount -Subscription $subscriptionId $context = Set-azContext -Subscription $subscriptionId $profile = [Microsoft.Azure.Commands.Common.Authentication.Abstractions.AzureRmProfileProvider]::Instance.Profile $profileClient = [Microsoft.Azure.Commands.ResourceManager.Common.rmProfileClient]::new( $profile ) $token = $profileClient.AcquireAccessToken($context.Subscription.TenantId) $header = @{ 'Content-Type'='application/json' 'Authorization'='Bearer ' + $token.AccessToken } $uri = [System.Uri]::new( "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.HybridCompute/machines/$machineName ?api-version=2024-07-10" ) $contentType = "application/json" $data = @{ location = $location; properties = @{ osProfile = @{ windowsConfiguration=@{ patchSettings=@{ enableHotpatching=$hotpatchStatus; }; }; }; }; }; $json = $data | ConvertTo-Json -Depth 4; $response = Invoke-RestMethod -Method PATCH -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; The Hotpatch tile now shows disabled after Opting out. The Enable hotpatching slider is turned off. Opt in Sample code: # Change the following params for your test machine. $subscriptionId = '' #Your subscription id $resourceGroupName = '' # your Resource Group $machineName = '' # Arc resource name $location = "" # The region where the test machine is arc enabled. $hotpatchStatus = $true # Do you want to opt-in ($true) or Opt-Out ($false) for receiving hotpatch without changing the license to get hotpatch. $account = Connect-AzAccount -Subscription $subscriptionId $context = Set-azContext -Subscription $subscriptionId $profile = [Microsoft.Azure.Commands.Common.Authentication.Abstractions.AzureRmProfileProvider]::Instance.Profile $profileClient = [Microsoft.Azure.Commands.ResourceManager.Common.rmProfileClient]::new( $profile ) $token = $profileClient.AcquireAccessToken($context.Subscription.TenantId) $header = @{ 'Content-Type'='application/json' 'Authorization'='Bearer ' + $token.AccessToken } $uri = [System.Uri]::new( "https://management.azure.com/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.HybridCompute/machines/$machineName ?api-version=2024-07-10" ) $contentType = "application/json" $data = @{ location = $location; properties = @{ osProfile = @{ windowsConfiguration=@{ patchSettings=@{ enableHotpatching=$hotpatchStatus; }; }; }; }; }; $json = $data | ConvertTo-Json -Depth 4; $response = Invoke-RestMethod -Method PATCH -Uri $uri.AbsoluteUri -ContentType $contentType -Headers $header -Body $json; The Enable hotpatching slider is turned on after the Opting In. Hotpatch Management To manage the Hotpatches you can leverage existing Windows Update APIs along with some additional functionalities that gives you even more control over the updates. Below is a sample code that allows you to scan for updates relevant to your machine. You can loop through the updates and determine if the updates will cause a reboot or not. Hotpatch updates should not cause a reboot unless any of the below two conditions is true: The device has a pending reboot from a previous update The device was on an update prior to the latest baseline update. So, when a hotpatch is offered during a hotpatch month it installs the latest baseline update followed by the hotpatch. The baseline update needs a reboot while the hotpatch itself is installed without a restart. # Create Update Session $session = New-Object -ComObject "Microsoft.Update.Session" $session.ClientApplicationID = "Sample Code" # Create Update Searcher and search for updates Write-Host "Creating Update Searcher and searching for updates.." $updateSearcher = $session.CreateUpdateSearcher() $searchResult = $updateSearcher.Search("IsInstalled=0 and DeploymentAction='Installation'") # If no updates found, exit if ($searchResult.Updates.Count -eq 0) { Write-Host "No updates found!" Exit } # Loop over each update in the Search result Update Collection foreach ($update in $searchResult.Updates) { Write-Host "Update title: '$($update.Title)'" Write-Host "Querying static 'ContainsUpdateBootstrapper' property.." # Query for static extended property # https://learn.microsoft.com/en-us/windows/win32/api/wuapi/nf-wuapi-iupdateex-get_extendedstaticproperty $containsUpdateBootstrapper = $update.ExtendedStaticProperty("ContainsUpdateBootstrapper") # If the update contains bootstrapper, perform pre-download and query for dynamic extended property if ($containsUpdateBootstrapper) { Write-Host "Update '$($update.Title)' contains update bootstrapper" Write-Host "Creating Update Downloader and performing pre-download of update bootstrapper.." # Create an update collection and add updates to download $downloadColl = New-Object -ComObject "Microsoft.Update.UpdateColl" $downloadColl.Add($update) # Create an Update Downloader and set the update collection to download $downloader = $Session.CreateUpdateDownloader() $downloader.Updates = $downloadColl # Perform pre-download to download only update bootstrapper # https://learn.microsoft.com/en-us/windows/win32/api/wuapi/nf-wuapi-iupdatedownloaderex-download2 $downloadResult = $downloader.Download2(1) if ($downloadResult.HResult -eq 0) { Write-Host "Successfully downloaded update bootstrapper" Write-Host "Evaluating dynamic 'DoesUpdateRequireReboot' property.." # Query for dynamic extended property # https://learn.microsoft.com/en-us/windows/win32/api/wuapi/nf-wuapi-iupdateex-evaluateextendeddynamicproperty $doesUpdateRequireReboot = $update.EvaluateExtendedDynamicProperty("DoesUpdateRequireReboot") if ($doesUpdateRequireReboot) { # If update requires reboot, skip download/install Write-Host "Update: '$($update.Title)' requires reboot, skipping" } else { # If update does not require reboot, it is a rebootless update, hence perform full download and install Write-Host "Update: '$($update.Title)' does not require reboot" Write-Host "Performing full download of update '$($update.Title)'.." # Perform full download of the update $fullDownloadResult = $downloader.Download() if ($fullDownloadResult.HResult -eq 0) { Write-Host "Successfully downloaded update: '$($update.Title)'" Write-Host "Creating Update Installer to install update: '$($update.Title)'.." # Create an update collection and add updates to install $installColl = New-Object -ComObject "Microsoft.Update.UpdateColl" $installColl.Add($update) # Create an Update Installer, set the update collection to install and install the updates $installer = $Session.CreateUpdateInstaller() $installer.Updates = $installColl # Install the updates $installResult = $installer.Install() if ($installResult.HResult -eq 0) { Write-Host "Successfully installed update: '$($update.Title)'" } else { Write-Host "Failed to install update: '$($update.Title)'!" Exit } } else { Write-Host "Failed to download update: '$($update.Title)'!" Exit } } } else { Write-Host "Failed to download update bootstrapper for update: '$($update.Title)'!" Exit } } else { Write-Host "Update '$($update.Title)' does not contain update bootstrapper, skipping" } } Below is a sample snippet of an update. This shows that the cumulative update does not require a reboot and that it was Hotpatch capable. This update will be installed as part of this update check. Use Azure Resource Graph to determine which machines are enabled for hot patching. Resources | where type == "microsoft.hybridcompute/machines" | extend hotpatchEnabled = tostring(properties.osProfile.windowsConfiguration.patchSettings.enableHotpatching) | extend hotpatchStatus = tostring(properties.osProfile.windowsConfiguration.patchSettings.status.hotpatchEnablementStatus) | project name, location, resourceGroup, hotpatchEnabled, hotpatchStatus | order by hotpatchEnabled desc In summary, effective management of hotpatching for Azure Arc connected machines requires a thoughtful approach that balances automation, security, and operational needs. By leveraging the provided sample scripts and APIs, organizations can streamline patch deployment while maintaining control over their environments. It is essential to rigorously test all automation in a development setting and adapt solutions to align with your company’s security posture. By embracing these strategies, organizations can proactively safeguard their systems, minimize downtime, and stay ahead in an ever-evolving cloud environment. If you have questions, please feel to reach out to our team: hotpatchfeedback@microsoft.com *** Disclaimer *** The sample scripts are not supported under any Microsoft standard support program or service. The sample scripts are provided AS IS without warranty of any kind. Microsoft further disclaims all implied warranties including, without limitation, any implied warranties of merchantability or of fitness for a particular purpose. The entire risk arising out of the use or performance of the sample scripts and documentation remains with you. In no event shall Microsoft, its authors, or anyone else involved in the creation, production, or delivery of the scripts be liable for any damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or other pecuniary loss) arising out of the use of or inability to use the sample scripts or documentation, even if Microsoft has been advised of the possibility of such damages.
Hotpatching for Azure Arc–Connected Servers: General Availability and Subscription Details
Effective July 16, 2025, Hotpatching for Windows Server 2025 on Azure Arc–connected machines will be generally available (GA) and transition to a paid subscription model. This post provides technical details on the service, the value of hotpatching for on-premises servers, and important enrollment information for customers. What Is hotpatching? Hotpatching enables you to install OS security updates on Windows Server without requiring a reboot. This technology, previously exclusive to Windows Server Datacenter: Azure Edition, is now available for on-premises and hybrid environments through Azure Arc. Hotpatching has been in public preview at no cost, but as of July 16, 2025, a monthly subscription fee of $1.50 USD per CPU core will apply. Why hotpatching for on-premises servers? Minimize downtime: Apply critical security updates without interrupting workloads or requiring planned maintenance windows. Improve security posture: Reduce the window of vulnerability by deploying patches as soon as they are available. Operational efficiency: Eliminate the need for frequent reboots, simplifying patch management for IT teams. Consistent experience: Use the same hotpatching process across Azure, on-premises, and hybrid environments with Azure Arc. Enrollment and billing To receive hotpatches on Windows Servers outside of Azure, customers must enroll their servers. The servers must be on the latest cumulative update released during a baseline month (January, April, July and October) by Microsoft on the second Tuesday of the month. Only enrolled servers will continue to receive hotpatches and be billed accordingly. Preview customers: If already enrolled during the preview period, then no action is needed to continue to receive hotpatches. If you enrolled in hotpatching during the Preview and do not wish to be billed after GA, you must disenroll your servers before July 16, 2025, to avoid charges. New customers: Enroll your eligible Windows Server 2025 machines via Azure Arc to activate hotpatching and start receiving updates. How to enroll in hotpatching To begin receiving hotpatches for your Azure Arc–connected Windows Server 2025 machines, follow these steps: Prerequisites Ensure your machine is connected to Azure Arc. Ensure Virtualization Based Security (VBS) is enabled and running. Confirm that the latest cumulative update from a baseline month (January, April, July, or October) is installed. Hotpatching is only offered if this requirement is met. Enrollment via Azure Portal Connect your server to Azure Arc. Navigate to the Windows Server resource in the Azure Arc portal. Click on the Hotpatch blade Check the box “I want to license this Windows Server to receive monthly hotpatches” and click on confirm under the hotpatch blade. Note: Enrollment operation takes a few minutes, so you may need to manually refresh the Azure portal to see the updated status. How to disenroll from hotpatching If you no longer wish to receive hotpatches or want to avoid billing after the preview period ending on July 16, 2025, you must disenroll from hotpatching service on Azure Arc portal. Disenrollment via Azure portal Go to the Azure Arc–connected server in the Azure Arc portal. Open the hotpatch blade. Uncheck the box “I want to license this Windows Server to receive monthly hotpatches” and click on confirm. Important: Disenroll before disconnecting the machine from Azure Arc. If you disconnect first, billing may continue for up to 30 days after the last connection. See this blog post for additional details. Disenrollment via API Set subscriptionStatus to "Disable" in the license profile payload. This action is synchronous and should reflect immediately, though portal refresh may still be required. Learn more If you’re interested in learning more, check out our April blog post and the on-demand session on Hotpatching and Update Management from our recent Windows Server Summit virtual event.[On demand] The hottest way to update Windows 11 and Windows Server 2025
Dive into hotpatching for Windows 11, version 24H2 and Windows Server 2025 machines connected to Azure Arc. Find out how to preview this new capability and get answers to common questions. Watch The hottest way to update Windows 11 and Windows Server 2025 – now on demand – and join the conversation at https://aka.ms/HottestWayToUpdate. To help you learn more, here are the links referenced in the session: Hotpatch updates Release notes for hotpatch public preview on Windows 11, version 24H2 Enterprise clients Release notes: Windows 11, version 24H2 - December 10, 2024 - KB5048667 December 10, 2024—Hotpatch public preview KB5048794 (OS Build 26100.2528) aka.ms/GetHotpatch Release notes for Hotpatch on Windows Server 2025 Datacenter Azure Edition Skilling snack: Hotpatch on Windows client and server For more free technical skilling on the latest in Windows, Windows in the cloud, and Microsoft Intune, view the full Microsoft Technical Takeoff session list.
Hotpatching on Windows
Hotpatching is an impact-less update technology which has been keeping the Azure fleet up-to-date for years with zero impact on customer workloads. Hotpatching is also available for Windows Server Azure Edition customers and we're working on making it available more broadly over time. This article describes how Hotpatching is implemented in the operating system.
