Actually...
Should be capable of using ACMEv2 protocol.
See:
Certbot 0.22.0 Release with ACMEv2 and Wildcard Support - Client dev - Let's Encrypt Community Support (letsencrypt.org)
The problem may lie in that it already issued a cert via ACMEv1 and now may need to be instructed to use ACMEv2.
Not to say that I recommend using such an old version.
Quite the opposite; There are many reasons to keep this and all software up to date.