When I suspend my PC I get an annoying popup dialog for authentication.

Anyone knows why, and how to disable it?

I have disabled locking after wake up from sleep, fwiw.

    6 days later

    That's odd, I don't have to authenticate to use Sleep on either of my Plasma systems.
    If you run this command in your terminal what's the output? Can you paste that in a reply?

    groups

    @TraceyC groups output:
    [myuser] dialout audio video cdrom lpadmin sudo scanner plugdev users fuse input sambashares

    @Staudey Yes, I installed it with autologin enabled, and I have disabled screen locking in the settings, both after waking up and the "lock screen automatically".
    But even with that turned off I get the lock screen on occasion.

    I have actually reinstalled Solus 3 times by now in order to troubleshoot. I think it has to do with the lock screen: it has happened every time after I get a lock screen (i.e. I get it despite having turned it off everywhere). After unlocking it my password, if I then do loginctl, sddm is listed as another user, besides from me, with a session.

    Last install was yesterday. I have suspended and woke up 2 times, and so far no lock screen.

    I will post again when it appears again. In the meantime let me know if you want any other output.

    (Forgot to mention that when that happens I can't shut down or restart, as it hangs seemingly waiting for some process to finish)

    Something to try is to add your user to the wheel group and see if you still see that pop up sometimes.

    sudo usermod -a -G wheel username

    I also don't see your username in that list, by default there should be a group that has the same name as your user. Your user should belong to it.

    If you still see the pop up, I recommend searching through the KDE bug tracker to see if anyone has reported similar problems there.

    Please let us know if any of the above helps. If there's a bug in our installed environment we want to fix it.

      TraceyC My username was what I indicated by [], i.e. myuser, so it's there.
      I will try wheel thing.

      So I just woke up my computer, and sure enough I got the lock screen. This time however I could barely login again. Multiple attempts just led me to a black screen. After I finally managed to login loginctl now ouputs:

      SESSION  UID USER   SEAT  TTY  STATE   IDLE SINCE
      1 1000 rincor  seat0 tty1 closing no        
      4 1000 rincor  seat0 tty4 closing no        
      6 1000 rincor  seat0 tty4 closing no        
      7 1000 rincor  seat0 tty4 closing no        
     c4  983 sddm   seat0 tty3 online  no        
     c5  983 sddm   seat0 tty2 online  no

      Things are really messed up after this login! I'm certain it's connected to the login screen.
      Anything you want me try right now?

          rincor

          That's really odd behavior I've not seen before. Have you tried searching the KDE bug tracker?

              TraceyC Yes, I did various searches but couldn't find anything that matches this bug.

              I actually think there are two bugs going on here:

              1. The session closing after unlocking the screen, which then requires authentication for various operations (suspend; mounting USB devices; reboot/shutdown)
              2. The fact that I get a lock screen at all despite having disabled it everywhere

                Having two sddm sessions is not usual, and may be the cause of the problem. Does it look this way right after you start the system and log in?

                  TraceyC No, on boot it looks like this:

                  SESSION  UID   USER   SEAT  TTY  STATE  IDLE SINCE
      1  1000 rincor  seat0 tty1 active no

                  I have enabled the lock screen again after wakeup. After entering the password it looks like this:

                  SESSION  UID USER   SEAT  TTY  STATE  IDLE SINCE
      1 1000 rincor seat0 tty1 active no        
     c1  983 sddm   seat0 tty3 online no

                  which I assume is still ok.

                  But literally while I was typing this reply the lock screen appeared all of sudden (never happened before), and now it looks like this:

                  SESSION  UID USER   SEAT  TTY  STATE   IDLE SINCE
      1 1000 rincor seat0 tty1 closing no        
     c1  983 sddm   seat0 tty3 online  no        
     c2  983 sddm   seat0 tty2 online  no

                  So now it's messed up again and I will need to authenticate on suspend.

                    it looks like a second sddm session is being initiated somehow, which I suspect is what's causing the undesired password prompt.

                    As a test, can you create a new user, and see if the same thing happens with that login? There may be an old setting or cache value that's contributing to this.