Updated existing TB installation following check for update under About Thunderbird from V45 to V68.12.1 on Mac OS 11.4. Each successive update read the my existing profile and once at 68.12.1 everything works - all local folders and email send/receive are normal as long as TB is left open. But when quitting and restarting TB the "profile cannot be loaded . . " message appears. I have looked in troubleshooting - Profile Folder and it points to Library - Thunderbird - Profiles - and to the correct profile name. Hard to understand how TB can use the profile to send and receive mail but then is not able to access it on startup. Please let me know how this might be fixed. Thank You.