Manual:$wgAjaxLicensePreview

Ajax: $wgAjaxLicensePreview
Use Ajax to preview licensing for uploads.
Introduced in version:1.11.0
Removed in version:still in use
Allowed values:(boolean)
Default value:true

DetailsEdit

Users can preview the licenses on Special:Upload before uploading media to the wiki. This setting is on by default and applies only if MediaWiki:Licenses has been created.