“Invalid nonce value! Please try again” message

I am getting the message “Invalid nonce value! Please try again or contact the administrator for help.” each time I test the form. Emails are not being sent.

I am only displaying name, email, message fields. I’m using the honeypot, but have disabled both the email confirm field and the GDPR checkbox.

Can you explain to me what the error is and how to fix it? Thanks.