If you rebuild from scratch, you can minimize downtime by
- creating new DO floating IP and switching DNS for domain to use the floating IP, then give it some time for DNS to propagate
- provision and deploy to new server, syncing DB and uploads
- test new server, probably using fake entry in local
/etc/hosts - put site on old server in maintenance mode (or something to prevent DB writes), sync DB one final time, and reassign floating IP to new droplet – downtime will be several seconds only
Normally it would help to post a little more info, e.g., which ansible task is producing the posted error, and output of the output’s suggested commands See “systemctl status php7.0-fpm.service” and “journalctl -xe” for details” (which will probably need sudo).
If you don’t want to create a new server, I think you’ll need to address the issue of provisioning a newer version of php on a server that already has an older version of php. A couple of sample threads related to that topic (but I think there are more): one and two.