Unable to debug .NET Core app

I'm having and issue with Visual Studio and a .NET Core API project. It's been working fine but something must have changed because I'm now getting the following output when trying to debug the project:

The program '[18032] dotnet.exe' has exited with code -2147450749 (0x80008083).
The program '[17688] iisexpress.exe' has exited with code 0 (0x0).
The program '[5500] iexplore.exe' has exited with code -1 (0xffffffff).

The event viewer is showing this error:

Failed to start process with commandline '"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\Extensions\Microsoft\Web Tools\ProjectSystem\VSIISExeLauncher.exe" -debug -p "C:\Program Files (x86)\dotnet\dotnet.exe" -a "C:\Projects\Utilities\API\src\API\bin\Debug\netcoreapp1.0\API.dll" -pidFile "C:\Users\username\AppData\Local\Temp\tmp742C.tmp" -wd "C:\BlueSky\Utilities\API\src\API"', ErrorCode = '0x80004005'.

I'm not sure why this is happening, if anyone has any insight into this it would be appreciated.

Do as fallow:

1. Close Visual Studio
2. Delete the project.lock.json file (if exists)
3. If above step won't help then try to remove .vs folder
4. Open Visual Studio as Administrator (the file will be restored and you shouldn't have problems anymore)

There is also an option to use Kestrel instead of IIS Express but that's just an workaround.