Thread:Project:Support desk/DB connection error: No such file or directory (localhost)/reply


 * 1) Rename your old directory to something else
 * 2) Create a new folder, with the same name, with the files for MediaWiki 1.18.1
 * 3) Move your old LocalSettings.php to the root of the new folder
 * 4) Run the installer

This worked for me for my cases, but you may have considerably more difficulties than me considering your huge version jump.