I suppose you had the class binaries in the .cache directory which were compiled using the Groovy 2.4 in Katalon Studio v8.x. Now you are on Katalon Studio v9.x with Groovy 3.x. So you need to clearn the project and rebuild it. The above 3 directories should be initialized.
I would suggest Katalon to deprecate the feature of caching class binary files in the ./cache directory entirely. In my opinion, it was a mistake. It improved nothing. It just added risk of strange behavior which @zahid.asim and others were annoyed. Many more users will be confused in future.