Hi there,
I created a marketing form with the form type "Subscription Center". This marketing form has a "Form level double opt-In" set up and will be embedded on our website.

Obviously, before we are embedding the form on our website, I would like to test the whole process to be sure it works. All the components are live and I created a form hosting website to get the script or iFrame for embedding.
To test the process I copied the link out of the iFrame from the form page and opened it in a new tab.
Opening the link a new tab, looks as follows:

I hope this error will not appear when I embed the form on our website. Clicking on "show form anyway" shows me the form I created:

After filling out the form, choosing the subscription and submitting I always get the following error:

Clicking on try again is not reloading the form. It is just a blank page. The same happens for the marketing page (Subscription Center) I created that contains the form.
I open the Full page URL that is under summary and filling out the form that is embedded in the marketing page and after submitting I get an error.


