I’ve the same 500 Internal Server problem when I updated to WordPress 4.4.
My hosting company said the error is caused by this:
[Thu Dec 10 04:05:50.228317 2015] [:error] [pid 7931] [client 18.104.22.168:10410] PHP Fatal error: Call to undefined function jeg_get_all_category_vc() in /nas/content/live/campusplus/wp-content/themes/jmagz-child/functions.php on line 39
Can you look into this? I’ve downgraded to WordPress 4.3 as of now due to theme incompatibility issue.