After the update this morning, photos can no longer find the photo library (libraries).... I can see the library, I can select the library but photos can't find it..
Even if I get photos to create a new library, it can't find that one either..
I had this problem before and eventually it was fixed after 3 or 4 further beta updates...
My photos / "Pictures" directory is on an external Pegasus RAID drive.
2013 Mac Pro,
MacOS 10.15.5 beta.