So it was able to load the project (after converting it). Yay!
The conversion was a little rocky - there were some odd error messages
and popups, but they don't seem to have affected the actual conversion.
Now I'm working and there's a message at the top of the screen:
No Scala SDK in module.
And a link:
Set up Scala SDK?
When I click on the link I get a popup "Add Scala Support", with a
selector to choose a library (and no options) and a button "Create" that
throws an exception. (error report 751607)
I'll see how things go. Hopefully I won't have to back up to 1.0.201 AGAIN.