The AbsenteeLandlord extension will automatically lock the database from any further changes if a sysop has not been on the wiki recently (determined by $wgAbsenteeLandlordMaxDays). This helps prevent dead or inactive wikis from becoming spambot targets. To unlock the database, a sysop simply needs to visit the wiki again.
By default this extension locks the database after 90 days without having an active sysop. If you would like to change this, e.g. to 60 days you will have to add the following line below the inclusion of this extension: