Oh no! Something has gone wrong (GNOME3)

Please, make us a favor, to all of us, you and we: Don't compare two systems which are separated by an abysmal distance. Thanks.
It is unnecessary. He's already gave up, as he/she said.
I'm sorry to read it. But the differences between he and me, it's that I don't want the "easy" way.
I really sorry to read that he is going to use only Ubuntu.
Ubuntu it's more GUI than code, but that it's another topic. It haves to one of its positive things that it is so graphic, perhaps it's what he want. Not bad. But if you want some "real", well, there are other distros.
Further investigation shows that it appears to be some sort of race condition. I edited /usr/local/libexec/gnome-settings-daemon-localeexec and changed the exec line to use truss in order to try to trace where it was getting stuck.

truss -o /home/wmoore/Documents/gnome-settings-daemon-truss.out exec /usr/local/libexec/gnome-settings-daemon

However after that change the hang stopped, even with --failsafe removed from .xinitrc. Suspecting the slight delay introduced by truss I then changed gnome-settings-daemon-localeexec to the following and that seems to have the same effect:

sleep 1
exec /usr/local/libexec/gnome-settings-daemon

To resurrect a slightly old thread, this still works and does the trick for me after I installed the official NVIDIA drivers. (I'm using an NVIDIA GeForce GTX 1070, with an otherwise vanilla setup.)
Good bye. I don't know if it'll be the right thing for you. We don't need you. But if you already gave up instead of fight to use it, it speaks a lot about you. Perhaps you are a smart person and you'll study this (in that case, well, there are at least 7-10 years of study). Or simply you gave up because it is too much for you and you want some easy-use (but that doesn't mean that it will be a good OS). In the second case, I can understand you. I've fight one time and again with this OS.
But you know what's the difference between you and me? I never gave up. I will be still here, but you not. Think about it.
But if you say that maybe in a few years you'll try to use it, well, there's no guarantee about that.
dont respond to me posts any more.
Something has gone wrong with GNOME 3 on FreeBSD about two years ago, as far as I remember. When gnome-shell (all versions after 3.18) got systemd as a dependency. While it is not bad modern DE (if do not take into account its dependencies), but, it seems, there is no future for it on FreeBSD, it is sad, but maybe one day someone will manage to patch new versions, to remove systemd dependency. I've read, that such patchs exist for OpenBSD and Gentoo, may be it is possible to adapt it for FreeBSD… Personally I stopped using gnome-shell two years ago, IMO it is much more practical to use lightweight WM-s (like x11-wm/fvwm2, here is my config), it's much more configurable, customizable, also it's working much more faster and much more stable (without any "Oh no!…" notifications).
Resurrecting again this post, I get the OP error message when my Thinkpad resumes into Gnome from suspend.
It seems related to some Gnome extensions I am using.
I solved the issue as follows:

1) at the beginning of /etc/rc.suspend I added:
gsettings set org.gnome.shell disable-user-extensions true

2) at the end of /etc/rc.resume I added:
gsettings set org.gnome.shell disable-user-extensions false

As you can see, the above two commands are invoked respectively before suspending and after resuming, and conveniently disable and re-enable the Gnome extensions. Perhaps the same strategy can be used before and after a reboot, for those who see this error when starting Gnome.