How to fix Rubymine having issues finding your Ruby SDK. I hit this when switching from rbenv to asdf.

RubyMine - project SDK problem (using asdf).md

problem:

Error configuring SDK: [...]. 
Please make sure that [... ruby path, from asdf or otherwise ...] is a valid home path for this SDK type.

solution that worked for me:

1. close RubyMine
2. delete .idea/ folder [assuming you can do so; you could probably edit some stuff inside if you needed to be precise]
3. re-open project in RubyMine

source