I also had this precise message today for the very first time. I’m on a MacBook Pro running Mac OS 12.4. What was new? I had just upgraded an hour or two earlier to the latest version 11.5 and the message coincided exactly with my mounting of my time machine backup disk. So I quit from Lightroom Classic, let my backup run to its conclusion, ejected the backup disc, then re-launched Lightroom Classic , no problem. But if I re-connect my backup disc, the message immediately returns. This has not occurred on any previous Lightroom version.