myxwiki.org has been upgraded to XWiki 15.3. If you own a wiki hosted there, you should have a look at the release notes for this version at:
Project Release Notes (XWiki.org)
You should automatically get an upgrade wizard for your wiki when you login as admin.
For more details, see the upgrade guide available at :
To be notified of the myxwiki.org server upgrade, you can follow myxwiki on Twitter: