Mailchimp Error

I am getting the following error with the plugin:
Debug Log
[2019-01-02 15:08:54] ERROR: Form 6188 > MailChimp API error: 400 Bad Request. Invalid Resource. Your merge fields were invalid.
– FNAME : Please enter a value
– LNAME : Please enter a value
Request: PUT https://us7.api.mailchimp.com/3.0/lists/0769270580/members/4675c973f03e964e1581c91036487897 – {“email_address”:”john*********@ya***.com”,”interests”:{},”merge_fields”:{},”status”:”subscribed”,”email_type”:”html”,”ip_signup”:”99.189.139.113″}
Response: 400 Bad Request – {“type”:”https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/”,”title”:”Invalid Resource”,”status”:400,”detail”:”Your merge fields were invalid.”,”instance”:”7ea3759b-f3dc-4604-8d12-87a1cf1b921b”,”errors”:[{“field”:”FNAME”,”message”:”Please enter a value”},{“field”:”LNAME”,”message”:”Please enter a value”}]}
[2019-01-02 15:09:21] ERROR: Form 6188 > MailChimp API error: 400 Bad Request. Invalid Resource. Your merge fields were invalid.
– FNAME : Please enter a value
– LNAME : Please enter a value
Request: PUT https://us7.api.mailchimp.com/3.0/lists/0769270580/members/4cc7278e7a58d3b5c59bbefe5ca90f92 – {“email_address”:”info@ea***********.com”,”interests”:{},”merge_fields”:{},”status”:”pending”,”email_type”:”html”,”ip_signup”:”99.189.139.113″}
Response: 400 Bad Request – {“type”:”https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/”,”title”:”Invalid Resource”,”status”:400,”detail”:”Your merge fields were invalid.”,”instance”:”93808ad2-8b48-4119-9f63-26329f9b6276″,”errors”:[{“field”:”FNAME”,”message”:”Please enter a value”},{“field”:”LNAME”,”message”:”Please enter a value”}]}
[2019-01-02 15:22:47] ERROR: Form 6188 > MailChimp API error: 400 Bad Request. Invalid Resource. Your merge fields were invalid.
– FNAME : Please enter a value
– LNAME : Please enter a value
Request: PUT https://us7.api.mailchimp.com/3.0/lists/0769270580/members/4cc7278e7a58d3b5c59bbefe5ca90f92 – {“email_address”:”info@ea***********.com”,”interests”:{},”merge_fields”:{},”status”:”pending”,”email_type”:”html”,”ip_signup”:”99.189.139.113″}
Response: 400 Bad Request – {“type”:”https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/”,”title”:”Invalid Resource”,”status”:400,”detail”:”Your merge fields were invalid.”,”instance”:”c1bba9ff-324f-4a3e-b2c7-0585e5f3b86b”,”errors”:[{“field”:”FNAME”,”message”:”Please enter a value”},{“field”:”LNAME”,”message”:”Please enter a value”}]}
[2019-01-02 15:23:14] ERROR: Form 6188 > MailChimp API error: 400 Bad Request. Invalid Resource. Your merge fields were invalid.
– FNAME : Please enter a value
– LNAME : Please enter a value
Request: PUT https://us7.api.mailchimp.com/3.0/lists/0769270580/members/4cc7278e7a58d3b5c59bbefe5ca90f92 – {“email_address”:”info@ea***********.com”,”interests”:{},”merge_fields”:{},”status”:”pending”,”email_type”:”html”,”ip_signup”:”99.189.139.113″}
Response: 400 Bad Request – {“type”:”https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/”,”title”:”Invalid Resource”,”status”:400,”detail”:”Your merge fields were invalid.”,”instance”:”ef6aed80-e09c-4e1a-9678-65ce72fc2dfd”,”errors”:[{“field”:”FNAME”,”message”:”Please enter a value”},{“field”:”LNAME”,”message”:”Please enter a value”}]}

Any help or suggestions appreciated.
Thanks,
John

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