Unable to connect to the Microsoft Visual Studio Remote Debugger: Operation not supported - Unknown Error

Mat Powers 21 Reputation points


I'm having an issue where I can't start a debugging session on a Azure App Service remote host. I'm receiving the following error:

User's image

Information that might be useful:

  • It's a .NET Framework 4.7.2 app.
  • We're on a Premium v3 App Service Plan
  • Remote debugging is On for the deployment slot
  • The Visual Studio version matches (2022)
  • We are not using any URL rewrites in the web.config
  • I'm on the latest version of Visual Studio (17.7.6)

I can see that from the server logs that the following requests are made during the attempt to connect:

Protocol Path Result
HEAD / 200
GET /DebugWarmUp 404

There are no further messages in the Visual Studio output window.

This is happening on multiple sites that I used to be able to remote debug, but due to the infrequency of needing to do this, I cannot remember the last time I was successful in doing so, and there have been multiple commits between now and then. It was at most a year ago, and we have upgraded to a better App Service package (Standard --> Premium) in that time, in case that might be relevant.

I'm at a loss as to where to look next to continue with troubleshooting this, seeing as there's so little in the logs and the error message is pretty useless.

Let me know if there's any vital information that I've left out?


Visual Studio
Visual Studio
A family of Microsoft suites of integrated development tools for building applications for Windows, the web and mobile devices.
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Azure App Service
Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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