Thread:Project:Support desk/URL format for mediawiki/reply (7)

You shouldn't mix alias and rewrite for this.

If you're using virtual host, drop the alias and rewrite rules and just use this:

DocumentRoot /var/lib/mediawiki RewriteEngine On   RewriteRule ^/?wiki(/.*)?$ %{DOCUMENT_ROOT}/index.php [L]

Be sure to include a  definition inside the VirtualHost