What does this error message mean?

Error 401 - Unauthorized - The user does not have permission to perform the action.

Error 404 - Not Found - The requested item was not found in the database.

Error 422 - Unprocessable Entity - This error typically occurs when the user attempts to save changes to an entity but has provided invalid data. We usually try to prevent this from occurring by disabling the save button if data is invalid, but there may still be cases where it occurs.

Error 400 - Bad Request - This error typically occurs when the user attempts to save changes to an entity but has not entered all mandatory fields. As above, in most cases we prevent this by disabling the save button if there are missing mandatory fields.