Hi there,
Hi Fionn - what exact version are you using? As far as I know, this message occurs if you are trying to open a LEAP area that was created in a newer version of LEAP, but you are using an older version of LEAP (typically a version before 2020.1.27).
Thanks for the quick reply Charlie. I am using the latest version (2020.1.56).
Did someone manually drop that .leap file into that folder? It shouldn't be like that. Suggest you move the .leap file to another temporary folder (delete it under LEAP Areas) then use the Area: Install from File menu option to install it into LEAP.
Don't know how that leap file got there, but after deleting it and pasting in the correct file contents, LEAP finally opened. Happy days!