This error is caused when a Publishable Field within the Contact Card includes a colon or semicolon. This will need to be removed from all fields in order to resolve the error.
  1. Navigate to Core 
  2. Settings > Custom Fields
  3. Within Publishable Fields, locate the Field Name containing a colon or semicolon
  4. Left click into the Field Name to remove the text
  5. Navigating away from the Text Field will save any changes immediately