Please refer the below troubleshooting article to fix the issue.
Let us know if that helps.
from the Macintosh HD > Users > [your user folder ... click "Go" on the selections on the top bar on the desktop (Menu Bar) > then click the "option" key > mouse down to the "Library" selection that should appear > click on that to open the "/Users/[your username]/Library/ folder
you should now find the appropriate folders to edit permissions. Just give your username the read/write permissions. I don't think you have to give everyone permission to read/write as others have stated.
I have tried all of the fixes suggested and none work, only setting light room up in as a new user has it loaded for me. This however is not what I want to do, will it load if a uninstall and reinstall?
Just tried your suggestion, LR is now working, Thanks for the tip.