Photo library won't import back on Mojave after Catalina I have downgraded to Mojave after the automatic installation of Catalina that have given me a lot of problems.
Now I have a Photo library that won't open back on mojave.
It's a 178GB library and I need it back.
Is there a way to do that?
I can offer you a work around.


Go to you Pictures folder
Right click your Photos library, "Show Package Contents"
All photos are in the "Masters" folder. Create a new Photo library and import.


At 178GB I'm guessing you have some level of organization, folders, etc. I'm unsure if that's recoverable.