When RT is upgraded, users can experience WSOD(White Screen Of Death), all the log will say is:
“Out of memory! Callback called exit.”. Not so informative eh?
The solution is pretty simple, run this query in the database:
“ALTER TABLE sessions CHANGE a_session a_session LONGBLOB;”
Then clear the table with:
TRUNCATE TABLE `sessions`;
Any logged in users will be logged out, but the problem should disappear.