Thread:Project:Support desk/Fatal error: cannot access private property/reply (3)

I'd suggest to download the latest 1.23 version and reupload it again on your server. This seems like you upgraded over an old installation and some files left unmodified with the old version.

It would be good if you unpack all new files on an empty folder and copy over your data (LocalSettings.php, extensions, and uploads if they're in subdirectories of the installation)