Error: Unable to Automatically Step Into the Server
Applies to: 
Visual Studio 
Visual Studio for Mac
Note
This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here
The error reads:
Unable to Automatically Step Into the Server. The debugger was not notified before the remote procedure was executed
This error can occur when you are trying to step into a web service (see Stepping Into an XML Web Service). It can occur whenever ASP.NET is not set up properly.
Possible causes are:
The web.config file for your ASP.NET application does not set debug to "true" in (see Debug Mode in ASP.NET Applications).
A version of ASP.NET was installed after Visual Studio was installed. ASP.NET should be installed before Visual Studio. To fix this problem, use the Windows Control Panel > Programs and Features to repair your Visual Studio installation.