You may need to run the command as if you don't have full write permissions to the wiki install directories under your current user.When untarring a tarball package normally a new directory for the new wiki version will be created and you will have to copy the old configuration files and images directory from your old installation directory: , export the files into a clean location, and then copy the old customized files into the new location as described in the previous section.Since Media Wiki 1.25, extensions use a new extension registration system.Previously your Extensions are being adapted to use the new extension registration system.If you don't have Git but you want to upgrade a lot of extensions, you might consider using mw Ext Upgrader.
You can upgrade the Media Wiki database in two ways: Either from the command line or from the web browser.
Extensions that are not adapted should use the old way of installing them. New variables may be added in newer versions, or some existing variables changed their type.
Refer to the installation instructions on the extension's page for more information. We usually try to use sane defaults for them, and in case of type change, be backwards compatible.
For performance reasons, some actions in the database are delayed, and are managed by the job queue.
Those jobs are stored in database and contain parameters with information about actions it should perform.