Unity: “Code Editor Application”

I was opening up an older project ( I believe it was a project from version 2020.X.X ) , and came across the error below:

After some quick searching around It turned out I needed to install the Visual Studio package in Unity. If I had to guess as to why this error came up I believe I may have needed to install the Visual Studio package to begin with. Here are the steps I took to solve it.

Setup 1: Open up the ‘Package Manager’.

Setup 2: Make sure ‘Packages: Unity Registry’ is selected, and search for the Visual Studio plugin, and install both.

Setup 3: Finally, go to Unity -> Preferences and adjust your External Tools accordingly as to which code editor you want to use.

This is what worked for me. Hopefully it does for you as well!