When attempting to add new fields to old surveys in survey123 connect I am getting an error code 400 service layer definition not found. The appears to be the case for any field that I enter even a simple integer at the end. Is this a common problem. Is this a common problem? Anyone else having this problem with older surveys? If I make a copy of the survey it works just fine.
The error you describe could occur if the feature service has been moved or delinked from the form. As you note, creating a copy would fix this as it creates a new feature service.