How to specify an app_offline template when using IISWebAppDeploymentOnMachineGroup?

I'm deploying a .NET 8 app (API in this case) through Azure DevOps Server 2022 to a Win Server 2022 with IIS.

Here is the yaml code:

- task: IISWebAppDeploymentOnMachineGroup@0
  inputs:
    WebSiteName: ${{ parameters.webSiteName }}
    Package: '$(System.ArtifactsDirectory)/${{ parameters.artefactName }}/*.zip'
    RemoveAdditionalFilesFlag: true
    TakeAppOfflineFlag: true

This works as expected, even the TakeAppOfflineFlag. However, I can't seem to figure out how to specify an app_offline file to use for this task. I always end up with an empty page, which is fine for the API, but I need to deploy a web app later.

The response is an html page with a body tag containing "Adding additional hidden content so that IE Friendly Errors don't prevent this message from displaying (note: it will show a ' friendly' 404 error if the content isn't of a certain size)."

I have tried the following:

• Putting an app_offline file at the root of inetpub
• Following this by specifying the appOfflineTemplate in the task input AdditionalArguments, but to not avail. It does not generate the same command as in the link and msdeploy simply fails with the code 4294967295 and that -appOfflineTemplate is not recognized. Example: "C:\Program Files\IIS\Microsoft Web Deploy V3\msdeploy.exe" -verb:sync -source:package='REDACTED' -dest:contentPath='REDACTED' -enableRule:AppOffline -appOfflineTemplate=app_offline-template.htm. Attempted values:
  • AdditionalArguments: -appOfflineTemplate=C:\inetpub\app_offline-template.htm
  • AdditionalArguments: -app_offline-template.htm

Any ideas? Thank you in advance.

You are not the first to ask about this,

https://github.com/microsoft/azure-pipelines-tasks/issues/13231

There are workarounds mentioned such as adding your own steps to fully control the app offline page.