What could be causing the error in the console when trying to integrate Mailchimp with Webflow and the form is not submitting?

If your Webflow form is not submitting and you see an error in the browser console while trying to integrate with Mailchimp, it’s typically caused by misconfiguration or security restrictions.

1. Check Form Action URL

• Webflow forms don’t natively support third-party integrations like Mailchimp without a proper form action URL.
• If you're using a form action method to post directly to Mailchimp, make sure you:
• Use the Mailchimp post URL provided in your Mailchimp embed code (usually from the form embed).
• The URL should look like: https://xxxxxx.list-manage.com/subscribe/post?u=xxxxxxx&id=xxxxxx.

2. Confirm CORS Restrictions

• Mailchimp does not allow cross-origin AJAX submissions, which means if you're trying to submit via JavaScript (default Webflow behavior), you’ll get CORS-related errors in the console.
• To work around this:
• You must disable Webflow's native AJAX submission.
• Add form attribute data-wf-ajax="false" to your form element.

3. Match Input Field Names Exactly

• Mailchimp expects field names like EMAIL, FNAME, and LNAME.
• Make sure your form’s input name attributes match exactly what Mailchimp expects.
• Webflow uses its own names ( email, etc.), so you’ll need to:
• Go to the element settings panel in Webflow.
• Manually update the input field name to match (e.g., EMAIL).

4. Ensure Hidden Inputs Exist (Especially Honeypot Fields)

• Mailchimp embed code often includes hidden inputs like b_xxxxxx_xxxxxx, which is a honeypot field for spam protection.
• If this required field is missing or renamed, Mailchimp will reject the submission silently or throw an error.
• Copy all hidden fields from the Mailchimp embed form into your Webflow form.

5. Remove Conflicting Custom Code

• If you’re using custom JavaScript to handle the Mailchimp form, review the console error specifically.
• Common issues:
• Fetch or XMLHttpRequest blocked due to CORS policy.
• Syntax errors in your custom code.
• Wrong method (should be POST per Mailchimp requirements).

6. Test Using Mailchimp's Embed Code First

• To isolate the problem:
• Try embedding the entire Mailchimp form (from their Embed Form option) inside an Embed element in Webflow.
• This bypasses Webflow’s form handling to verify if the issue is Mailchimp or Webflow related.

Summary

Your Webflow form may fail to submit to Mailchimp due to AJAX-based submissions (CORS issues), incorrect form action URLs, input names not matching Mailchimp expectations, or missing required hidden fields. Disabling AJAX on the form and ensuring field names and structure match Mailchimp’s form are key to a successful integration.