Could not copy "obj\Debug\netcoreapp1.1\server.dll" to "bin\Debug\netcoreapp1.1\server.dll"

As I am developing in Radzen, periodically (I haven't pinpointed the exact steps to duplicate) the app won't Run and displays ... dotnet: C:\Program Files\dotnet\sdk\2.1.4\Microsoft.Common.CurrentVersion.targets(4106,5): warning MSB3026: Could not copy "obj\Debug\netcoreapp1.1\server.dll" to "bin\Debug\netcoreapp1.1\server.dll" ... in the Output window. I've gotten around this by opening the Windows Task Manager and killing the dotnet Background Process. image

I thought I'd make you aware of it.

We have seen this problem but haven’t been able to find a way to reproduce it predictably and unfortunately don’t know what is causing it. It looks as if the dotnet process is locking the file for some reason.