Mono backend is suddenly not installed anymore, can't build and play mode vomits errors

Unity Engine
1

My entire projects is broken. Can’t build, all scripts cause thousands of errors in the console. Going back to the last changeset that worked makes no difference. Reinstalling the Editor makes no difference. I didn’t even change anything, I just booted up my computer and opened the project.

UnityEditor.BuildPlayerWindow+BuildMethodException: Error building Player: Currently selected scripting backend (Mono) is not installed.
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (UnityEditor.BuildPlayerOptions options) [0x002da] in <5f40cdb07bd44d76a23dad985a4ec283>:0
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (System.Boolean askForBuildLocation, UnityEditor.BuildOptions defaultBuildOptions) [0x00080] in <5f40cdb07bd44d76a23dad985a4ec283>:0
UnityEditor.EditorApplication:Internal_CallGlobalEventHandler ()

2021.3.8f1 / Win 10

2

Okay so apparently Unity just decided it was time to silently switch my build target to dedicated server.

I could not have possibly changed it because the last thing I did yesterday was to build and shut off the computer, and today I only started it and opened the project.

Thank god for this thread , I probably would have never figured out what happened otherwise and nuked my system.

3

I’m sorry you’ve had this issue. Please consider using proper industrial-grade enterprise-qualified source control in order to guard and protect your hard-earned work.

I assume the server-build setting change above would have been instantly obvious as it would be in ProjectSettings.asset, which you would be source controlling.

Personally I use git (completely outside of Unity) because it is free and there are tons of tutorials out there to help you set it up as well as free places to host your repo (BitBucket, Github, Gitlab, etc.).

You can also push git repositories to other drives: thumb drives, USB drives, network drives, etc., effectively putting a complete copy of the repository there.

As far as configuring Unity to play nice with git, keep this in mind:

https://discussions.unity.com/t/736093/3

Here’s how I use git in one of my games, Jetpack Kurt:

https://discussions.unity.com/t/807568/3

Using fine-grained source control as you work to refine your engineering:

https://discussions.unity.com/t/826718/2

Share/Sharing source code between projects:

https://discussions.unity.com/t/719810/2

Setting up an appropriate .gitignore file for Unity3D:

https://discussions.unity.com/t/834885/5

Generally setting Unity up (includes above .gitignore concepts):

https://thoughtbot.com/blog/how-to-git-with-unity

It is only simple economics that you must expend as much effort into backing it up as you feel the work is worth in the first place. Digital storage is so unbelievably cheap today that you can buy gigabytes of flash drive storage for about the price of a cup of coffee. It’s simply ridiculous not to back up.

“Use source control or you will be really sad sooner or later.” - StarManta on the Unity3D forum boards