Fix for the “Out of memory! Callback called exit.” error in Request Tracker (RT)

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.