Hi @Dave,
Might you have made any local custom changes to settings.php that prevented an automatic update? Could you attach a copy of your emonpiupdate.log?
You need to copy default.emonpi.settings.php
$ cp /var/www/emoncms/default.emonpi.settings.php /var/www/emoncms/settings.php
See the exact same issue on another thread:
It could be you are running an old SD card image version, I will investigate.