I have upgraded 2.9 to 3.3. After upgrading course images is not showing.
I have check all possibility. like
I have given full (777) permission to moodle and MoodleData folder.
I have deleted localcache and cache from MoodleData folder.
I have try with remove course image and then try with new course image.
I have check database mdl_files table "contenthash" this is perfect entry.
I have check moodledata folder filedir directory there is file also store.
I have also Purge all caches and clean theme caches as well.
I have try chnage another theme.
I have check inspect web page there is showing me 303 error in Network tab.But still there is no images not display.