NOTE!! Please be careful after updating AS2020.3.1.x to AS2020.3.1.5 and want to install the suggested Kotlin update (1.4.21 to 1.4.30 RC IJ"somewhat"), it rendered the shared 2020.3 store unusable, and you get this "Missing essential plugin: org.jetbrains.android Please reinstall Android Studio from scratch". It won't help. You need to delete (or at least rename) the path "C:\Users\[your_user_name]\AppData\Local\Google\AndroidStudioPreview2020.3" before you do any installation. Do NOT copy your settings from there when you install from scratch (you just inherit the errors). You need to rebuild your settings, (if you haven't exported your settings sometimes) (as i didn't)... The kotlin plugin seems the one to blaim.
I strongly eager AS/IJ engeneers to make a "repair" tool when this type of errors plugin related errors occures.
You don't need to remove the suggested folder if your previous 2020.3.1.x version starts successfully. You can still run that version. But you may not start your 2020.3.1.5 even if you install ("or recopies") new installation.