Unable to start debugging. The startup project can

Question

I'm trying .NET Core today inside Visual Studio 2017. However, it seems I'm unable to debug the application even with barebone Hello World project.

Every time I try to start the project, the following message box appear:

I've searched similar issue and come across this thread: Unable to start debugging. The startup project could not be launched. VS2015

I tried every single answer there and nothing worked in my end.
Is there something I missed?

Thanks in advance

Answer 1

I had the same problem (Visual Studio 17.3 and 17.4). I was able to solve today. It turned out that the cause was an extension. After deactivating this extension I was able to debug again.

Edit: In my case it was the "Arduino GDB for Visual Micro 2017".

Answer 2

After experiencing the error dialog in the original question and I followed the suggestions provided here and on similar SO topics, with no success. Thinking my project was the problem I created a brand new, "Hello World" .NET Core console application.

I could not start the debugger from this brand new project as well. I decided this was a problem beyond my project or solution files. So I decided to repair my Visual Studio 2017 installation, I was running VS 2017 15.5.1.

To repair VS 2017... start Visual Studio Installer, under the Installed section\Visual Studio Professional (my edition is Professional), look for the More [down arrow] option to the right of [Modify] and [Launch], from the More drop-down choose Repair.

This took quite some time (I left for a couple hours), but upon return both the new Hello World and my NETCore application would launch in the debugger.

Answer 3

Under your solution (not project), there should be a file called global.json with content like this:

"sdk": {
   "version": "1.0.0-blah-blah"
}

Go to the command line and run: dotnet --version. This will give you the default dotnet version. Replace "version" value with that, save the solution, restart Visual Studio and give it a shot again.