Since the firewall is on a remote site and the upgrade caused the ISP to issue a new IP Address, I was unable to connect to pfSense (or the entire site) following upgrade. A site visit was required (I have temporarily added the site to my own Dynamic DNS subscriiption with another provider.)

The DNSExit dynamic DNS service has worked flawlessly for over 5 years, however with this upgrade it stopped working.

Prior to upgrade log entry:
/rc.newwanip: phpDynDNS (xxxx.yyyy.com): (Success) IP Address Changed Successfully!

Post upgrade log entry:
/services_dyndns_edit.php: phpDynDNS (xxxx.yyyy.com): PAYLOAD: <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <html><head> <title>502 Proxy Error</title> </head><body> <h1>Proxy Error</h1> <p>The proxy server received an invalid^M response from an upstream server.<br />^M The proxy server could not handle the request <em><a href="/RemoteUpdate.sv">GET /RemoteUpdate.sv</a></em>.<p> Reason: <strong>Error reading from remote server</strong></p></p> <hr> <address>Apache/2.2.15 (CentOS) Server at www.dnsexit.com Port 443</address> </body></html>