When using the segments functionality, The following error may be shown.
The application has experienced a system error. The reported error message was: Mailchimp returned an error: Each criteria row must contain the keys "field" (merge3), "op" (eq) and "value" ().
The happens when the segment criteria is similar to the following:
"ConsId is blank"
This is shown below:
The workaround is to do the following:
This is a problem as of v2.0.20 although a MailChimp fix may make this and earlier version work.