Manual:$wgAjaxUploadDestCheck

Ajax: $wgAjaxUploadDestCheck
Enable Ajax check for file overwrite, pre-upload.
Introduced in version:1.11.0
Deprecated in version:1.38.0 (Gerrit change 722358; git #6c4ac7dd)
Removed in version:1.41.0 (Gerrit change 949596; git #ee4472fe)
Allowed values:(boolean)
Default value:true

Details edit

Enable Ajax check for file overwrite, pre-upload.

This is not related to the deprecated action=ajax ($wgAjaxExportList) functionality.