OK, I know, I know, I still have two sites that are on multiuser WordPress (in addition to this site). I've migrated just about everything but two sites. But a good reminder was the JetPack reported the three sites down (the umbrellas sites and the two remaining subsites) on DigitalOcean.

As a reminder the quick debug for this is to:

1. First thing I do is a hard reboot. Since I have weekly snapshots, it's kind of for free to do this since these sites really don't change at all.
2. That didn't work so time to go in and try to check the services. The most common problem is out of memory errors with mysql, so login and do a service mysql status and it is running fine. Huh.
3. Then look at Apache2 with service apache2 status and I get this strange error saying that a Let's encrypt file names something like one-of-my-sites-0001.pem is missing.
4. Come to figure out that in some release of certbot, it now no longer used the -0001, so the trick is to edit the /etc/apache2/sites-enabled/003-one-of-mysites-le-ssl.conf and get rid of that filename extension and all is good.

Then the next thing I discover is that as I've migrated off of multiuser wordpress, I've had a single certificate serving multiple domain names, so for example site1.com and site2.com. So what if site 2 migrates off. The only fix is that you have to do a certbot delete -d site1.com and it wipes out the entire certificate and then you recreate it with certbot run -d site1.com only and this is how you bet rid of site2.

If you don't then on every certbot renew, it will see site2.com and generate an error.