Visual Studio Community on MacOS: Projects with non-local source (http://…) not supported

Question

I am completely new to C# development and Visual Studio, and just started working on an existing project for an app server. I downloaded Visual Studio Community for MacOS and opened the project's solution (.sln) file. I have managed to get the solution to build, but every time I open it, a popup window appears, displaying two warnings like

Projects with non-local source (http://...) not supported. 'http://localhost:<some port number>'

I couldn't find any references to this specific message. What does this mean? Should I worry about it?

Answer 1

It means your solution has a project defined in it that VS doesn't understand. This typically happens when a solution is originally built on one platform and then is opened on another.

For solutions built originally on Mac OS, which uses Mono for .NET, generic projects use the .mdproj type. VS for Windows doesn't understand these. Likewise, there are project types that Windows VS can create that VS for Mac doesn't understand. This is what produces the error you see.

In my case, on Windows VS the solution contained a "web site" folder (eg globe icon). This was really just a folder with HTML files in it, but the solution defined it in a way that the Mac OS VS didn't understand. My solution was to fire up the solution in Windows, remove the html project, and add a Solution Folder (plus all the child folders and files). VS doesn't treat these Solution Folders as projects, and so on the Mac there was no problem opening the solution.

Some background: https://www.monodevelop.com/documentation/solutions-and-projects-explained/