Creating a new project, then exporting it to .json, then adding it back in works fine. It creates the new database successfully.
can you test if the file that you downloaded is a valid JSON ?
Okay, well, when I went to GitHub and downloaded the raw output as a .json, that worked. Right clicking and saving-as apparently did not save it correctly. Maybe it was my fault. I really appreciate all your help. Sorry about the hassle.
No worries! Thanks for the confirmation!