Previously, named accepted FORMERR responses both with and without an OPT record, as an indication that a given server did not support EDNS. To implement full compliance with RFC 6891, only FORMERR responses without an OPT record are now accepted. This intentionally breaks communication with servers that do not support EDNS and that incorrectly echo back the query message with the RCODE field set to FORMERR and the QR bit set to 1. GL #2249

The question section is now checked when processing AXFR, IXFR, and SOA replies while transferring a zone in. GL #1683

This should be just documented, not neccessary and probably impossible to do an actor for this. Just note if it breaks communication with server, then the remote server needs fixing.