"The script class needs to derive from ScriptableObject..." ??

Instance of xxx couldn’t be created. The script class needs to derive from ScriptableObject and be placed in the Assets/Editor folder.

I keep getting this on random things since upgrading to 2018.3.9. It doesn’t happen until something errors and I leave play. Then anything with a custom inspector that I click on says “Multi-object editing disabled” and throws the above error, even basic Unity Terrains. A restart fixes the behavior.

Any ideas?

I’m also experiencing this now that I upgraded to 2019.2.8f1. I see there is another thread with the same issue: Custom Editor Inspector [Bug]

Has there been any solutuion to this?

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Hello! the issue you’ve linked to is already fixed in 2018.4.11f1, 2019.2.9f1, 2019.3.0b6, 2020.1.0a5 and above. You can find more information about it here: https://issuetracker.unity3d.com/issues/creating-assembly-definition-files-makes-the-editor-not-pick-up-custom-inspectors-until-restart

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I still get this. 2018.4.23

Instance of *** couldn’t be created. The script class needs to derive from ScriptableObject and be placed in the Assets/Editor folder.

@Domas_L
I’ve come to notice that this only crops up when I switch build target to Linux. I work on Windows 10 but export my builds to both Win10x64 and Linuxx64. I just exported a hotfix, which resulted in switching back to Windows as the target, but now the majority of my scripts won’t render in the editor showing the “The script class needs to derive from ScriptableObject” even though they are standard and in some cases very simple Monobehaviours.

I’ve also noticed it crop up when a export results in me leaving the target platform as Linux and then quitting and coming back the next day still targetting Linux.

Targeting windows and restarting fixes the problem.

I’m running 2018.4.23

It’s hard to say what could be causing this issue without having seen the setup - could you please submit a bug report with a small repro project for further investigation?

I’m on version 2022.3.7f1 and I have the same issue.

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same issue on 2022.3.10f1

same issue on 2022.3.33f1