An internal error occurred: ?:0: attempt to index a nil value Cannot pick photos for collections

I had an exclamation point on jpgs in a folder  2020 Apr renamed to 2020-04.  (I presume I renamed it in Explorer) I did not move the photos.  You have two options to fix the ! problem.  Overwrite or ?  I'm not sure which I did.  Now, when I use b or I click on the circle to pick pictures to put in a quick collection, I get the error above no matter what folder I use. I do not know whether these two actions are related.  It occurs in Develop and Library modules

This is Lightroom Classic on Windows.