pfSense error on restoring xml config

My pfSense is running v2.4.5 with several packages installed, I had a need to restore an earlier config backup, when I navigate to the login page I get the following error:

PHP ERROR: Type: 64, File: /etc/inc/, Line: 51, Message: require_once(): Failed opening required ‘Net/IPv6.php’ (include_path=’.:/etc/inc:/usr/local/www:/usr/local/captiveportal:/usr/local/pkg:/usr/local/www/classes:/usr/local/www/classes/Form:/usr/local/share/pear:/usr/local/share/openssl_x509_crl/’)

In Negate’s forum this has come up and looks related to packages getting mixed up between releases.

I had changed the option for updates to version 2.4.5 so I ought not to get any 2.5 updates (packages cannot be installed without doing so).

However, when restoring a config does it check the latest branch for updates and get stuck?

So if I stay on an old release and then try to restore an old backup will I always get this error if I have packages installed ?

The router is up but the GUI isn’t accessible.