Why a form in my workflow cannot be filled out by a client if it was used in the past?

This error happens due to misconfiguraiton of your forms.

If you would like to use a form in a portal, please make sure that the form settings called "Allow the client(s) to create multiple instances of this form" and "Data Source" are ticked off.

The options WERE NOT designed to work with workflows but only for questionnaires sent on stand alone basis. The 2nd of these options is actually an option used when you create your own catalog of data that needs to be referenced by other quesionnaires. You need to speak to us to configure that option properly.

If the first of these options is turned ON, your client will not be able to fill out a fresh new workflows that uses this form.