Continuing a bit from above, I managed to get some systems to upgrade from Ubuntu 14 to 16.
Now, after that's done, the systems aren't able to do any subsequent upgrades.
I know this is not the latest version of the kernel on my "patching server":
root@FOO:/etc/apt# apt-get install linux-generic-lts-xenial
Reading package lists... Done
Building dependency tree
Reading state information... Done
linux-generic-lts-xenial is already the newest version (4.4.0.142.148).
The following package was automatically installed and is no longer required:
libio-string-perl
Use 'apt autoremove' to remove it.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@FOO:/etc/apt#
I've done a apt-get update
to make sure I'm pulling down any new lists of packages. An apt-get upgrade
after that turns up nothing to update, which is definitely not right if everything is working.
I'm going to keep troubleshooting and adding information here as I come up with anything that might be valuable.