One good thing to have happened recently is the rise of Let's Encrypt, bringing https to all websites without all the hassle you previously had to go through to get a certificate.
One not quite so good event recently was the switch by Let's Encrypt to certificates signed by their own ISRG X1 root, and more excitingly the expiry of the prior DST Root CA X3 signing certificate.
My experience of this is that most things just worked, but I'm still seeing odd cases where clients can't connect. Generally, browsers work just fine; CLI tools are a bigger issue.
This might be due to a couple of issues. Sometimes the software itself guesses wrong (older openssl 1.0.2 for example); sometimes the system's CA bundle of trusted root certificates needs updating.
For a while now, the Tribblix package repositories have been served over https and the zap tool for package management has been configured to use https. There are cases where it falls foul of the above issues.
This might occur on older Tribblix releases - I've seen this on m22, for example.
It turns out that curl fails, but wget works. Again, that's an example of the inconsistency in behaviour that I see. You need to update the CA bundle on m22, but if the package update tool is broken that's a bit tricky.
There's an ugly hack, though, because zap will try wget if it can't find curl. So just move curl out of the way temporarily:
mv /usr/bin/curl /usr/bin/curl.t
zap update TRIBca-bundle
mv /usr/bin/curl.t /usr/bin/curl
and you should be good to go again.
There's another way, of course: edit the *.repo files in /etc/zap/repositories to change the URL from https to http. That's not particularly recommended (although the packages are signed and the signatures are checked).
One thing that last hack demonstrates is the value in using simple text files.