Fatal exception of type MWException - mediawiki

Question

I recently installed MediaWiki in localhost on Debian 7 System. But after the installation, I got the exception Fatal exception of type MWException. I reviewed all reported bugs, but they do not apply to me.
PHP 5.4.4
phpmyaddmin....

Answer 1

As written in the comments, edit your LocalSettings.php file and add this line at the very end:
$wgShowExceptionDetails = true;
Try reloading the page that gives you that error. You're likely to see what's called a backtrace... here is my example:
#0 /Users/user/www/extensions/LocalisationUpdate/LocalisationUpdate.class.php(553): LocalisationUpdate::filename('it')
#1 /Users/user/www/extensions/LocalisationUpdate/LocalisationUpdate.class.php(36): LocalisationUpdate::readFile('it')
#2 [internal function]: LocalisationUpdate::onRecache(Object(LocalisationCache), 'it', Array)
#3 /Users/user/www/includes/Hooks.php(255): call_user_func_array('LocalisationUpd...', Array)
#4 /Users/user/www/includes/GlobalFunctions.php(3883): Hooks::run('LocalisationCac...', Array)
#5 /Users/user/www/includes/cache/LocalisationCache.php(796): wfRunHooks('LocalisationCac...', Array)
#6 /Users/user/www/includes/cache/LocalisationCache.php(426): LocalisationCache->recache('it')
#7 /Users/user/www/includes/cache/LocalisationCache.php(310): LocalisationCache->initLanguage('it')
#8 /Users/user/www/includes/cache/LocalisationCache.php(245): LocalisationCache->loadItem('it', 'fallback')
#9 /Users/user/www/languages/Language.php(3978): LocalisationCache->getItem('it', 'fallback')
#10 /Users/user/www/languages/Language.php(230): Language::getFallbacksFor('it')
#11 /Users/user/www/languages/Language.php(189): Language::newFromCode('it')
#12 /Users/user/www/includes/Setup.php(497): Language::factory('it')
#13 /Users/user/www/includes/WebStart.php(161): require_once('/Users/user/3d...')
#14 /Users/user/www/index.php(55): require('/Users/user/3d...')
#15 {main}
The first line is the one that stopped the execution, causing the exception. If you can identify the problem (in my case it's the LocalisationUpdate extension) it can be very easy to fix. Again, in my case it's enough to open again LocalSettings.php and comment out or delete the line:
require_once( "$IP/extensions/LocalisationUpdate/LocalisationUpdate.php" );

Answer 2

There could be a problem with caching, try to use
$wgMainCacheType = CACHE_NONE;