Xfce: switching user causes frozen black screen

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twolf
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Xfce: switching user causes frozen black screen

Post by twolf » Sun Feb 05, 2017 5:18 am

Clicking Switch User lead to a black screen with a cursor in the top left corner. It stays that way forever. Happens every time.
Also, clicking New Login in the administration menu has the same effect.
This happens also with fresh new users.
Loggin off users works instead.

I read a post debating the same issue with Cinnamon DE, so I don't know if this issue is Xfce-specific.

Waiting for help
Thank you

chrisonmint
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Re: Xfce: switching user causes frozen black screen

Post by chrisonmint » Sun Feb 05, 2017 2:09 pm

I see this on Cinnamon Mint 17.3 and have for a while (since 17.1). I get the black screen with blinking cursor not every time i switch user, but probably once a week and cannot spot a pattern to it.

You seem to be in the wrong TTY, so pressing control, alt and F8 brings you back to the login screen. If that doesnt work, ctrl-alt-F1 takes me to a text-based login TTY where i can log in and reboot with a "sudo shutdown -r now" command.

The bug (I assume) is in the mint display manager (MDM) which is the software which handles logging in, user switching etc. If you login to a text TTY then you can try "sudo service mdm restart", but it doesnt help on my system (and might need a different command on mint 18.x).

You can try control-alt-backspace to restart the X system too, that might be a good work around.

My only option is to reboot, either the hard way (long press the power button = BAD!) or by the sudo shutdown route.

Hope some of this helps, good luck!

twolf
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Re: Xfce: switching user causes frozen black screen

Post by twolf » Sun Feb 05, 2017 4:19 pm

Hi Chrisonmint
I forgot to mention my Mint version: I recently installed 18.1 (XFCE).
Unfortunately none of the workaround you suggested work for me, except for hard reboot.
I also suppose it's a MDM issue, regardless of desktop environment.
I activated NDM debug logging in its preferences, but I don't see anything understandable to me.

chrisonmint
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Re: Xfce: switching user causes frozen black screen

Post by chrisonmint » Wed Feb 15, 2017 4:12 pm

Hi twolf, were you able to switch to another TTY? If you can, then you likely need a different command to restart the MDM display manager - things changed with INIT vs upstart (I think).

Do some googling for it and report back.

chrisonmint
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Re: Xfce: switching user causes frozen black screen

Post by chrisonmint » Fri Feb 17, 2017 4:45 pm

twolf wrote:Hi Chrisonmint
I forgot to mention my Mint version: I recently installed 18.1 (XFCE).
Unfortunately none of the workaround you suggested work for me, except for hard reboot.
I also suppose it's a MDM issue, regardless of desktop environment.
I activated NDM debug logging in its preferences, but I don't see anything understandable to me.
Hi twolf, any progress on this? I did some googling and remembered a github bug tracker for this issue with Cinnamon. Supposedly fixed in 17.1 but then back with 17.3 and 18:
https://github.com/linuxmint/mdm/issues/90

twolf
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Re: Xfce: switching user causes frozen black screen

Post by twolf » Mon Feb 20, 2017 11:15 am

Hi Chrisonmint

Unfortunately no progress yet.
As also reported here: viewtopic.php?f=56&t=173115
the cause could lie in the combination of MDM and some (how many?) nvidia cards. Would you confirm ?
Actually these were my recent test:

- Lenovo G500s + Nvidia Geforce + LM 18.1 XFCE = issue in user switching

- Same Lenovo G500s with VirtualBox LM 18.1 XFCE virtual machine (no Nvidia card detected) = no issue

- Dell Latitude E6400 (no Nvidia card) + LM 18.1 XFCE = no issue

:(

chrisonmint
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Re: Xfce: switching user causes frozen black screen

Post by chrisonmint » Tue Feb 21, 2017 8:40 am

twolf wrote:Hi Chrisonmint

Unfortunately no progress yet.
As also reported here: viewtopic.php?f=56&t=173115
the cause could lie in the combination of MDM and some (how many?) nvidia cards. Would you confirm ?
Actually these were my recent test:

- Lenovo G500s + Nvidia Geforce + LM 18.1 XFCE = issue in user switching

- Same Lenovo G500s with VirtualBox LM 18.1 XFCE virtual machine (no Nvidia card detected) = no issue

- Dell Latitude E6400 (no Nvidia card) + LM 18.1 XFCE = no issue

:(
Sorry to hear that. I have Intel integrated graphics (its a 1st generation i5). The "black screen" occurred this week. User switching into an account which was already running - I briefly saw the accounts lock screen with password box, then the screen turned off. I wonder if it is a mis-applied power saving thing? No keyboard or mouse activity could turn the screen back on so I had to do a hard-reset.

In the past, the bug has just dumped me in a blank TTY with flashing white cursor on the top left of the screen. Then I can recover it by switching to a text TTY and logging in to restart MDM.

twolf
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Re: Xfce: switching user causes frozen black screen

Post by twolf » Fri Mar 17, 2017 5:40 am

Hi, just an update.

I tried replacing MDM with LightDM (removing MDM to avoid any conflict). LightDM works but gives the same issue when trying user switching.
So I'm thinking MDM might not be accused.

I'm confused :(

This is a very annoying issue, having a multi-user installation.

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Pjotr
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Re: Xfce: switching user causes frozen black screen

Post by Pjotr » Fri Mar 17, 2017 7:17 am

twolf wrote:Hi, just an update.

I tried replacing MDM with LightDM (removing MDM to avoid any conflict). LightDM works but gives the same issue when trying user switching.
So I'm thinking MDM might not be accused.

I'm confused :(

This is a very annoying issue, having a multi-user installation.
Use ordinary logout instead, and hide "user switch" from the Whisker menu:
https://sites.google.com/site/easylinux ... ser-switch
(item 2.8, right column)
Tip: 10 things to do after installing Linux Mint 19.2 Tina
Keep your Linux Mint healthy: Avoid these 10 fatal mistakes
Twitter: twitter.com/easylinuxtips
All in all, horse sense simply makes sense.

twolf
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Re: Xfce: switching user causes frozen black screen

Post by twolf » Fri Mar 17, 2017 9:41 am

Thanks Pjotr, but it's exactly what I already do.
This hides but does not fix the issue, being forced to log out is quite a different situation.
Unfortunately it does not equal at all the benefit to switch session without worrying about closing/saving other users' applications and open files: that's what a real multi-user system should do.

twolf
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Re: Xfce: switching user causes frozen black screen

Post by twolf » Wed Apr 05, 2017 3:08 pm

One more update: I made another attempt with odd results.

Suspecting the issue may concern my Nvidia graphic card and/or its proprietary driver, I disabled it switching back to Nouveau open source driver.

First of all, after rebooting I found myself in front of a black screen (it's the second time it happens to me: enabling Nvidia proprietary driver and afterwards going back to Nouveau breaks something in X start, even in a fresh installation. That's another bad issue, but here it's out of scope).
Fortunately hitting Ctrl-Alt-...(and many keys I don't remember :roll: ) I could log in and give startx.
After that change I tried to switch user: instead of the usual freezing black screen with cursor, a window opened with a message explaining I could not switch user because I had "no access to the console".

Now, I can't understand if I managed to get some more information about my issue or if that message was only due to an unconventional way of starting X.

Do anyone skilled know what that "no access to the console" means ? Could it be the main cause of the issue ?

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