Roslyn compiler server reports different hash version than build task

Question

I've built an ASP.NET Core 3.1 app in Visual Studio 2019.

The app was compiling previously and I was able to debug it on the same computer. However without making any changes to the app, i suddenly started getting the error message "Roslyn compiler server reports different hash version than build task"

Downloading the repo and debugging on a different computer worked okay, however it's not a resolution for the existing computer.

Answer 1

What is happening is that compiler was "partally updated" by the visual studio installer. This is a setup issue in Visual Studio. If you could run https://aka.ms/vscollect.exe and upload the zip file in the temp directory to a new issue on Developer Community the setup team should be able to get to the bottom of this.

In order to resolve your issue you will want to run "repair" the VS intaller.