User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-43826407-20201124175546/@comment-1038387-20201125164757

The old editor was built on the 2006 editor. It is no longer compatible as of version 1.32. UCP is version 1.33, and retrofitting it to bring it back would require that specific, high labor and low reward task for every future update, holding back further progress. There are two newer editors, the 2010 editor (Source Editor) and the 2017 editor (Visual Editor and Visual - Source).