PHP 5 safe mode

PHP's safe_mode is an ill-concieved, broken-by-design setting in PHP that is supposed to make broken scripts safe. It was deprecated in PHP5 and removed in PHP6 (see the PHP documentation). MediaWiki can run with safe_mode enabled, but many of the advanced features will not work or need additional configuration.

To turn off safe mode, put this into your php.ini file: safe_mode = Off

If you cannot turn safe_mode off (such is the case with many shared webhosts), please consider finding a new host. If that is out of the question, read the next section for methods to enable some things with safe_mode on. It is recommended that if you do have access to php.ini, that you turn safe_mode off instead of using the methods described below.

There is a parameter to index.php called safemode - that is completely unrelated.

Making your wiki work with safe_mode
To make image uploads and deletions work in your wiki, you need to create the images/archive, images/temp, images/deleted, and images/thumb directories and make them all writable by your webserver (chmod 777). Then, set the following in your LocalSettings.php file: