Form stopped working

Hello,

My Formidable form worked all the time. but suddenly it stopped working. When you click “send”, you recieve a new page with an error ({“8”:”This value must be “,”9”,….)

Is it possible it doens’t work because of other plugins?

https://www.tricket.be/index.php?plugin=formidable&controller=forms&frm_action=preview&form=contact2

https://www.ads-software.com/plugins/formidable/