mercury hadn't been rebooted since I set it up in 2020-03.
Get a spare server named mercnew and configure it to the point where it could be brought on line in a few hours.
- rsync --archive -v /local/ root@mercnew.bonmot.ca:/local/
- install all the packages in 2020 mercury move
Back on mercury itself:
- apt upgrade - 50-odd packages including MariaDB
- "Err:8 https://packages.sury.org/php stretch InRelease The following signatures were invalid: EXPKEYSIG B188E2B695BD4743 DEB.SURY.ORG Automatic Signing Key <deb@sury.org>"
- apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys B188E2B695BD4743
- needed to install dirmngr in order to fix the bad key
- this triggered another 30 php7 & 8 updates
- reboot again