After some frustrations with a few updates while I was still new to Manjaro, I came across a couple of forum posts by @akin2silver and @koshikas that led me to this process for all my updates. This removed the likely source of many of the update problems (relying on pamac-gui) I encountered and it solved the obstacle of losing the laptop’s wifi access to the network while updating in TTY. Even though there is a way to log off the Plasma desktop and get access to wifi in TTY, I found this procedure simpler to follow.
The first part is while you are still in Plasma, using Yakuake (or Konsole) –
Run sudo pacman-mirrors -f 5 [this will update the mirror list with 5 fastest up to date mirrors]
Run sudo pacman -Syuw [this will only download the update packages]
Now that the updates have been downloaded (but NOT installed yet), save and close any open applications
Logout [press Ctrl+Alt+Del and then click logout]
At the Login screen, press Ctrl+Alt+F3 for TTY3
Login on TTY with your username/password
Run sudo pacman -Su [this will install the packages you just downloaded]
When the update has completed,
Run systemctl reboot
Don’t forget to run a pacdiff -s once you’ve logged back in.
And one more thing to keep in mind. I had to find out the hard way so perhaps I can spare you the problems (some requiring a reinstall) that I ran into. Don’t fall behind with updates. You might get away with skipping or missing one, but it’s best not to make it a habit. Check this forum regularly and watch for update announcements. I usually check the forum posts for the problems that are being discussed, to see how posters are solving them, before I actually do the updates myself.