New error message on trying to delete from disc x-marked images

This error used to occur a lot in years past. Two possible solutions help some but not all:

1. Go to File > Plug-in Manager. Select each plugin in turn, and in the Status panel on the right, click Disable.  A couple of plugins, most notoriously the Logioptions plugin by Logitech, could cause this error.  (Even if you don't use plugins, some of these plugins get installed automatically by other apps, so check Plug-in Manager.)

2. Try resetting LR's preferences:
https://www.lightroomqueen.com/articles-page/how-do-i-reset-lightrooms-preferences/

LR sometimes soils its preferences file, and resetting it can fix all sorts of wonky behavior. That article explains how to restore the old preferences if resetting doesn't help.