So yesterday, my DNS provider had problems. I started up the iMac, intending to access my router’s web interface to change my DNS settings. But I couldn’t launch apps. My system was slow and frozen/laggy. Even my offline password manager didn’t want to launch. Same with Pages. Apps bouncing in the Dock for minutes on end.
I actually had to boot up my Windows 11 laptop to make the change. In seconds.
Why does Mojave do this? I assume it has something to do with Gatekeeper, but it’s so annoying!
Do modern versions of MacOS still behave this way? It’s not a good look to have to rely on Windows to fix a basic connectivity problem because your Mac is too busy throwing a hissy fit.
I suspect it depends on the nature of your DNS problems.
If you disconnect from the network, apps launch. If Apple’s authentication server is not accessible, they should also launch. But if the DNS name resolves to the wrong data, so the requests are sent but the reply never arrives, that could easily lead to all kinds of things hanging.
Sadly, this is life on the modern Internet.
One thing I do (which you might also want to do) is I run my own DNS server. I do this so it can resolve host-names for all the devices on my home LAN, but it also means I’m not beholden to my ISP’s DNS server (my server resolves everything by accessing the root servers and walking from there). So my DNS will work as long as I have any IP connectivity to the Internet (and if I don’t, it will still resolve names for my LAN).
What you can also do when something like this happens is to switch to a good third-party free DNS service, like Cloudflare (1.1.1.1 and 1.0.0.1) or Quad9 (9.9.9.9 and 149.112.112.112, with IPV6 if you need it as 2620:fe::fe and 2620:fe::9) or Google (8.8.8.8 and 8.8.4.4, IPV6 2001:4860:4860::8888 and 2001:4860:4860::8844). These servers should be extremely reliable.
macOS runs online-required checks on apps before it launches them.
If the notary service can’t be reached a whole load of weirdness can happen.
That Apple server went down for a short while in Nov 2020 and people worldwide couldn’t launch apps. This raised concerns for obvious reasons.
After that Apple made some changes, but only for future products. So you are likely using an old version of macOS that is still susceptible to the problem.