ERROR: Contact Form 7 > Mailchimp API Error: Bad Request. Invalid Resource.

Hi

I’m getting this message in a website where it used to work fine.

I’ve noticed this bug because I’ve just configured a new website and I realized that only EMAIL, FNAME and LNAME was stored in Mailchimp.
So I checked the other website, where it used to work, and I realized that it fails too, but even worse because this one do not register any data in MC.

Here you have the error log:

[2022-04-13 17:13:17] ERROR: Contact Form 7 > Mailchimp API Error: Bad Request. Invalid Resource. Your merge fields were invalid.
- COUNTRY : Please enter a value
Request:
POST https://us2.api.mailchimp.com/3.0/lists/xxxxxxxxxx/members
{"status":"pending","email_address":"doma***@do*****.es","interests":{},"merge_fields":{"FNAME":"John","LNAME":"Doe"},"email_type":"html","ip_signup":"88.44.99.11","tags":[]}
Response:
400 Bad Request
{"type":"https://mailchimp.com/developer/marketing/docs/errors/","title":"Invalid Resource","status":400,"detail":"Your merge fields were invalid.","instance":"xxxxxxxx-xxxx-xxxx-xxx-xxxxxxxxxxx","errors":[{"field":"COUNTRY","message":"Please enter a value"}]}

It’s a bit strange because it says “Please enter a value” but no field was empty. In fact all data is received by email. The email which sends CF7.

So I wonder what can it be wrong.

I did my checklist:
– API and Audience ID are correct
– Plugin shows all Audiences and I could also renew the list
– CF7 form has all needed form items (as I’ve said, the old site used to work and forms were not modified)

What else can I check ?

Many thanks in advance.

Regards.