I have moved the website from TEST subdomain to MAIN domain, and have encounted several issues, on of them is crucial and IMPORTANT : 
--Contact form (Create Oportunity in CRM) not working anymore. Any idea where and what to fix?
After populating all fields, I get error next to the SUBMIT button :   An error has occured, the form has not been sent. 
V16, inserting new deafult form doesnt help.
If I change the contact form from OPORTUNITY to create TICKET, email, or whatever, then it works.