Hi liannem ,
Which version of Lightroom are using?
With Lr closed go to the location where your catalog resides(By default it is Pictures/Lightroom)
Delete the .Lock file with the same name as your catalog.For instance in the Picture below it is Lightroom4 catalog.lrat.lock
In your case it will be Lightroomcatalog.lrcat.lock(Lightroom6/cc)
Let us know if that helps
When i deleted the .lock file, it won't work..
But when i rebooted the laptop, then it started!
Thank you very much
With LR closed go to the folder where the LR catalog is stored and delete the .(dot)lock (Catalog name .lock) file. If you don't have the OS set to show File Extensions you will need to turn that option on first.
Thanks for your solution, this indeed works for me luckily!