All Forms Not Submitting

Guys,

I have posted on the official support forum with a ticket but that was 12 hours ago. I upgraded from basic paid to the next level last night to add the MailChimp plugin and since then all my form are broken. I upgraded all available plug ins today with the same result.

Complete the form – hit submit – error message form not submitted, see form for errors- all the entered data is gone and no errors appear in the form. Even a basic form with three fields name and email will not submit.

I urgent need some help as every form is broken and I have some quite intricate forms.