问题
While attempting to upgrade joomla using the button, I receive the server error 500. I have read this joomla forum post which related to my problem, but the update_site table in my server doesn't have any blank entries.
回答1:
probably your hosting server is weak. So it can not handle this kind of process. I suggest: 1) Make a full back-up and restore on localhost, then upgrade to 3.3.4. Make a full back-up and override your old joomla also database.
2) Change hosting company. By the way, after check those tips: http://www.joomshaper.com/blog/joomla/how-to-speed-up-joomla-3-3-3-4-and-template
来源：https://stackoverflow.com/questions/25080652/how-can-you-fix-server-error-500-received-when-upgrading-from-joomla-3-1-5