Win 10 and latest version of LR Classic. When I open LR I get the message that the catalog is already open and to close the other version and relaunch lightroom. I checked in task manager and do not see another application using any LR catalogs. I can also select and older catalog and it does open okay.
Worked, thanks Ian. Any idea why or what caused this file to be created. LR is working fine after I deleted the *.lock, but just now when checking the directory the catalog is in I see the lock file is back. Not causing a problem right now though.