Okay, here is the solution for anyone running an old version of OpenmBalena:
The problem is that ACMEv1 was deprecated recently, but the cert-provider included in OpenBalena hasn’t been updatd to use ACMEv2.
Here is what I did to fix it. On the Server running OpenBalena:
# Find out the id of the cert-provider container
docker ps
# Run bash in the cert-provider container
docker exec -it <mycontainer> bash
cd /root/.acme.sh
# Get the latest version that will support ACMEv2
./acme.sh --upgrade
# Register a new account on LetsEncrypt
./acme.sh --register-account --server letsencrypt
# Set it as default
./acme.sh --set-default-ca --server letsencrypt
# Find the folder containing your cert and cert config
cd /usr/src/app/certs/api.<your-domain>
# Edit the config file. Only vim is available
vi api.<dour-domain>.conf
Replace all references to https://acme-v01.api.letsencrypt.org with https://acme-v02.api.letsencrypt.org.
Save and exit.
Run the certificate updater (with debug to see that everything is working)
"/root/.acme.sh"/acme.sh --cron --home "/root/.acme.sh" --debug
Main references for finding the solution: