Error while saving new form

Hi Team,

We're running a multisite website with 100 websites.

When we will create a new form by plugin Gravityforms we get the error: "Error while saving your form"

The strange thing is that if we create a new website and add en new form. It won't work. We will get the error.

But the older websites won't get the error. It works fine to create a new form.

Do you have any idea how to fix this?

Thank you in advance.

Stijn