Photos library won't open after Mojave upgrade

Read suggestions from prior string and tried them, they did not work. When using the Command + Option to open a library and select Repair, I get 5% complete and no further progress. My Photos Libraries are on an external drive. Photos was working as of July 23, 2019. My Photos Libraries are on an external drive. If I leave the Photos window, clicking the Photos icon on the dock does nothing. If I click quit on Photos dock icon, the Photos window appears with the spinning 'wait' symbol. I'm using Mojave version 10.14.5. Photos.app is Version 4.0.