PHP Fatal error: session_start(): Failed to initialize storage module: user (path: /tmp) in User.php on line 159
Alright, I've got it. A quick Google search brings me to this page:
http://bugs.php.net/bug.php?id=25876
and one suggestion is to:
As suggested by mivox on Feb 12 in comments to bug 26038, which seems to be a duplicate of this one, I added a line in my apache.conf: php_value session.save_handler files
I added this to my .htaccess file, and immediately was able to see the index page of the MediaWiki. Why, I'm not really sure. Here's what I know:
* the /tmp directory is used by a number of other PHP installations to save sessions, and there are easily one hundred saved sessions in there. I can't delete them, as per one suggestion, because, well, that'd suck for those folks.
* I think the big culprint, however, is my parent .htaccess file, which was created by Drupal (a PHP CMS) and myself. Within that file, amongst other things, are the following definitions:
php_value session.cache_expire 200000 php_value session.gc_maxlifetime 200000 php_value session.cookie_lifetime 2000000 php_value session.auto_start 0 php_value session.save_handler user php_value session.cache_limiter none
Notice the save_handler set to "user", which also appeared in the error message pasted above.
So thus the solution, as per the above suggestion, was to reset the save_handler to the default setting in my /etc/httpd/php.ini file, which was "files". Once I did that, everything was magical.