Looks like i have same problems (but personally-can’t establish rdp connection).
But sudo pacman -Syu shows no available updates-/ I should wait for repos syncing or i can do something by myself? Sorry for question, i’m arch noob, btw-))
No worries.
If you happen to see some lone qt6 package upgrades then delay committing the update (or ending the desktop session) until the plasma-workspace (and some other) packages are upgraded as well.
I have also modified the thread title so as to hopefully make the situation more clear.
PS.
Somewhat of a tangent .. but I would bet hard earned cash that we would have seen a fraction of these occurrences if it were not for the prevalence now of update notifiers such as arch-update and cachy-update. Aw well.
Yeah, it seems that parts of the upgrade were available prematurely or the other way of looking at it, parts of the upgrade were not available on time. I think the general solution is to make sure that Plasma Workspaces is being updated when Qt 6 is being upgraded. Ideally, QT6 upgrades like these would come with / be packaged with version limit
It’s nice of you to assume that I am waiting for a notifier to let me know about upgrades rather than obsessively upgrading every couple of hours 
also having the same issue [zen 5]Plasma desktop broken system not booting due to sddm failing due to disabled RDseed however this thread is not in Issues & Assistance as it should plus it’s only related to zen5 where due to a security vulnurability the newer kernel would disable the rdseed. newer versions upgrades didn’t fix the issue
Then its not the same issue?..
It does seem to be related to the same update and the same end result. SDDM is crashing, but fully updating doesn’t seem to solve the issue.
The thread here is solved because the error encountered by some users last week was directly due to an incongruence between plasma-workspace and qt-* packages.
If your issue is not that then it is not the same.
That issue is solved by having the correct package versions (update).
If your issue is not then it is not the same.
If you have those same package versions and you encounter another (or even the same .. though its not really the same is it?) error .. then it is also not the same issue.
Or we could put it the other way around;
This thread is not about a particular hardware component, kernel options, or firmware. While your issue is.