Does anyone know what this error means when saving a new field to a content type?

Questions and Answers
8

Yes, I can confirm this happened in v3.5.4 as well, I tried to create new project, rather than migrating from 3.0.0.beta16, everything works fine until I tried to change/add some field in collection.

{"error":{"contentType.attributes.chapter_number":["contentType.attributes.chapter_number field cannot have keys not specified in the object shape"]}}