Today I saw an error message trying to run a web test. I added some validation rules to a web test then tried running it. Also hovered over the Server Explorer tab at the same time.
I have reproduced this error; it happens if you click Run Test while hovering over Server Explorer at the same time. The error persists until you expand Server Explorer.
The test could not be run because of the following exception: Assembly is still being loaded. (Exception from HRESULT: 0x80131016)
The "EntityDeploy" task could not be loaded from the assembly C:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Data.Entity.Build.Tasks.dll. Assembly is still being loaded. (Exception from HRESULT: 0x80131016) Confirm that the ,UsingTask> declaration is correct, and that the assembly and all of its dependencies are ready