error message is displayed when trying to save a form that is not a
process form, because it requires a Display name that has to be
manually included by the user.
Bizagi 10.x and 11.x
you create an Add form for a table
or a reusable form, and you save it once you have made your changes,
Bizagi prompts an error messsage.
forms require a Display Name. Bizagi creates an automatic name for
process forms but it does not do it for reusable forms. Thus, in
reusable forms a Display name is required, and if it is not included
Bizagi will not be able to save the form.
Go to the Form Basic Properties and give the form a Display name.
Then, you will be able to save your form.