MediaWiki/Support

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1146 ("table doesn't exist") errors

See the upgrade instructions at MediaWiki/Upgrading for details.

Stale PHP Process (?)

My wiki stopped working, accessing any page resulted in a "500 Internal Server Error" page. The HTTP error log showed a "Premature end of script headers" error.

Switching on debugging by setting

$wgDebugLogFile         = '/home/<username>/wikilogs/wiki.log';
$wgDebugRedirects       = true;
$wgDebugComments        = true;

eventually got me the error message

SQL ERROR: Lock wait timeout exceeded; try restarting transaction

I then noticed that there were three processes called php5.cgi. Killing them resolved the problem.

As a guess, it looks like mediawiki isn't entirely safe from deadlocks. Also, the lock wait timeout problem isn't handled too well, as the process appears to die without writing anything, resulting in that "Premature endof script headers" condition.

***Note that sudden appearance of "Premature end of script headers" 500 errors may also be purely a result of Dreamhost administrators temporarily misconfiguring Apache etc. "hiccups", and no fault of Mediawiki or the WikiSysop, and not a cause for wild debugging goose chases. Always contact Staff when you see such messages. *** Jidanni 11:46, 17 August 2009 (UTC)

Changing User Default Preferences

To change the default preferences for users who are not logged in and/or new accounts, you can check out this article.