Lock screen not accepting correct password to unlock

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1

I have a relatively new kubuntu 25.10 installation. I’ve installed a bunch of stuff, most recently VMware Workstation Pro, but it’s only been a few days since this was a fresh installation. I just left the machine for ~25 minutes, and when I got back, I found it had auto-locked, but when I entered my password, the lock screen told me it was wrong.

At first I thought, “Did I get pwned by something I did to get VMware working properly?” The only way to do that was to run third-party code as root. But, after some searching around, I found I could switch to another VT, log into the console, and then run loginctl unlock. This worked; I was repeatedly able to unlock the session (which is in the middle of doing important stuff, so thank goodness I didn’t have to kill it).

I found a forum post somewhere (on ServerFault I think?) where someone said they’d had this problem, and what had fixed it for them was resetting the password to what it was already set do by running passwd username as root. I tried this, but it didn’t solve the problem for me. If I press Meta-L right now, I won’t be able to unlock the session, but if I Ctrl-Alt-F4 (just the one I pressed at random), I can log in at the console prompt with the exact same credentials, and this works fine, and loginctl lists several sessions, the first of which has ID 3, and loginctl unlock 3 unlocks the locked session. Ctrl-Alt-F2 switches back to an unlocked session.

How do I diagnose this? What is going wrong with the specific way that the lock screen is trying to check my password?? Is it something I can fix?

At present, the work-around of switching to another console and unlocking it using loginctl works, but it’s a bit of a pain in the butt. :stuck_out_tongue:

KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.2
Kernel Version: 6.17.0.6-generic (64-bit)
Graphics Platform: x11

Let me know what else to provide/look up.

2

are you running a VM?

is it actually the VM lock screen you are trying to interact with?

did you set a different password for the VM lockscreen?

3

Thanks for the reply! It is not a VM. Running on bare metal. :slightly_smiling_face:

4

I made a recording of it:

In this video:

  • I visibly set my password to “abc123”
  • I lock the workstation
  • I enter “abc123” at the unlock prompt and click on the eye to show that I typed it correctly
  • I try to unlock and it rejects the password (*this is the problem)
  • I switch to another VT and log in using the new password
  • I run loginctl unlock–session
  • I switch back to the GUI VT, showing that the session is now unlocked