Unable to start process after change in the Multiple Subform Creation Form.

In Multiple Subform, you have to set up both table columns and creation/edition form. However this can get out of sync by making changes to the creation/edition form. By doing that user gets no warning that he can break something and no error on the broken form with the multiple subform. But when he deploys the project and tries to start the process, gets a vague warning:

Unable to complete your request. The following exception occurred: (TypeError) : Cannot read property 'f' of undefined.