After automatic upgrade to newest 3.3 version (31/10) by starting Score, the Musecore will be shut down.
After automatic upgrade to newest 3.3 version (31/10) by pop up window when starting the MuseScore, the MuseScore (V. 3.3) will be shut down automatically after answering question in the pop up box : "The previous session quit unexpectedly. Restore Session ?"; " Yes or No". Both actions for "Yes" or "No" will shut down the MuseScore immediately !!
But after uninstall and reinstall the Ver 3.3 (restart window each time), upgrade version 3.3 still come up the above pop up box.
After answer "No". It seems ok now.
All seems OK now !