Comment 3 for bug 1811063

I ran into this again with the 'hotsos' snap. It's frustrating because you get no warning that the snap isn't being updated. It does log this to syslog repeatedly:
Oct 08 13:33:06 optane snapd[2463]: snapstate.go:1334: cannot update "hotsos": snap "hotsos" requires classic confinement

But a plain "snap refresh" makes no mention and a "snap info hotsos" shows that the installed version is old but otherwise does not remark why or that there is a problem.

The only way to realise this is to run "sudo snap refresh hotsos" and then it complains with the same exact same error as the install phase:

$ sudo snap refresh hotsos
[sudo] password for lathiat:
error: This revision of snap "hotsos" was published using classic confinement and thus may perform
       arbitrary system changes outside of the security sandbox that snaps are usually confined to,
       which may put your system at risk.

       If you understand and want to proceed repeat the command including --classic.

I think this could really do with improvement to:
- List an error in the CLI output from "snap refresh"
- Make it more clear in the "snap info hotsos" output that the version is outdated and why
- For desktops, have the snap store pop up an alert about it, since you're much less likely to check the logs on a desktop compared to a server