There is a very bad problem with the "Blank screen" function in Ubuntu 17.10. I refer to the setting accessed via Settings->Power->Blank Screen. This seems to actually perform a screen lock, since I need to enter my password after un-blanking the screen. (However, given the behavior described below it's not clear exactly what this function actually does - maybe it just logs you out? maybe it reboots the machine?)

The problem is that a simple screen lock, which one would expect to lock the screen without affecting the state of any applications, in fact closes all applications that are open when the screen lock activates. In other words, if you have the screen lock set to 5 minutes, and you walk away from your machine to get a sandwich or whatever, when you come back and unlock the machine all your apps have closed without saving their state. So far, the only work-around I have found is to entirely disable screen locking in Ubuntu 17.10. My question is, how can this be fixed so that screen locking works properly - that is: the screen locks on schedule after a period of inactivity, and when unlocked all applications that were running are still running?

I am asking a new question for the following reasons:

1) The existing answers to (and comments on) this question do not address the issue, and in fact misrepresent the actual problem in ways that make me think the comment writers have not understood what is happening;

2) I cannot usefully address that question because I do not have sufficient reputation to either upvote the question or comment on it, and I cannot answer the question because I have no idea why this problem occurs;

3) I will probably never achieve a reputation of 15, much less 50, on StackExchange. Which is fine, that's not among my life goals.

4) But this question is important and deserves to be addressed. It is a drastically unacceptable bug.

  • This is a bug with Ubuntu. It is being tracked here. And has also been reported here and here – Gabriel Fair Jan 13 at 0:20

I use a 5 minute screen blank on 16.04, 17.10 and 18.04 beta, and it works as expected for me. You might also want to check launchpad bug reports, but I suspect that something else is causing problems with your system than the lock screen and blanking alone. For example, I wonder if some extension is crashing the gnome-shell (or something equiv if you are using a different desktop)?

You might check logs e.g. journalctl -b0 to look for suspicious errors in and around the time of the blank or the unlock. journalctl is better than dmesg for this because it provides human readable dates for logged events.

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  • Indeed, it seems that Wayland crashes soon after blanking the screen. If I set my session to "Unity under xorg", everything seems to work OK. – JKna Apr 10 '18 at 22:27

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