We are in the process of upgrading the wiki software. For now, it's not going as expected. I would recommend to not create new contents until the server is stabilized.
Or, instead of expecting people to not edit the Wiki, you could add like a line of code into LocalSettings.php to disable people from editing the Wiki. But that's just my suggestion.
I guess that was the right approach but I'm no expert wiki admin yet 
The wiki is now updated and seems to be working fine. I will de-activate it next time before doing any update. Thanks for the suggestion.
The wiki is now updated and seems to be working fine. I will de-activate it next time before doing any update. Thanks for the suggestion.And for the record, this is what you'd like to insert into LocalSettings.php:
Code:
$wgGroupPermissions['*']['createaccount'] = false;
$wgGroupPermissions['*']['edit'] = false;
$wgGroupPermissions['user']['edit'] = false;
$wgGroupPermissions['sysop']['edit'] = true;
You could replace the last true with false if you want absolutely nobody to edit pages.$wgGroupPermissions['*']['edit'] = false;
$wgGroupPermissions['user']['edit'] = false;
$wgGroupPermissions['sysop']['edit'] = true;
Ok. That's quite simple actually. Since I did it during the night (US time, it was day for me in Japan), I was not expecting many people to edit and was expecting it to be fast. It just took more time than expected.