This error took me a while to resolve, so I thought I'd throw it out as a discussion item so that anyone else with the issue had a resource. The message occurred when I was trying to publish a survey from Survey123 Connect. Here's a screenshot:
As it turned out, I was using EDITOR as a name for one of my fields. That isn't in the list of reserved keywords, but when you try to publish, it will generate this message. Took me a while to troubleshoot, but renaming it EDITOR_1 fixed the problem.
If you encounter other error messages and their solutions, feel free to add on to the discussion!