Cannot lock session (intermittent issue)

[olivierperes]

 * Cinnamon version (cinnamon --version): 4.6.6
   - Please specify if you are using the daily builds PPA: no
     (https://launchpad.net/~linuxmint-daily-build-team/+archive/ubuntu/daily-builds).
 * Distribution - (Mint 17.2, Arch, Fedora 25, etc...): Mint 20
 * Graphics hardware *and* driver used: Intel Corporation UHD Graphics 620 (Whiskey Lake) (rev 02), driver: i915
 * 32 or 64 bit: 64
 * Attach /home/<username>/.xsession-errors, or /var/log/syslog
[xsession-errors.txt](https://github.com/linuxmint/cinnamon/files/4959398/xsession-errors.txt)

Issue Locking the session sometimes fails.

Steps to reproduce Unfortunately, this is unpredictable as far as I can tell. Sometimes, when I click Lock Screen in the Mint menu, nothing happens at all. Retrying does not solve the issue. Rebooting the PC does solve it.

Expected behaviour Clicking Lock Screen in the Mint menu should lock the session.

Other information

Configuration info, if applicable If this bug report is related to an Applet, Desklet or Extension, please paste (or use a pastebin service) the offending extension's settings, if it has any. You can obtain this by opening its configuration, clicking the 'hamburger' button in the upper-right corner of the window, and selecting "Export to a file". Please be sure to review the contents and remove any personal data it may contain.

[ItzSwirlz]

This seems the most important part of the log.

Cinnamon warning: Log level 8: nma_mobile_providers_database_lookup_cdma_sid: assertion 'sid > 0' failed Cinnamon warning: Log level 128: posix_spawn avoided (automatic reaping requested) (fd close requested) Cjs-Message: 11:00:30.302: JS LOG: [LookingGlass/info] Hiding XAppStatusIcon (we have an applet): nm-applet ** Message: 11:00:30.507: nemo-desktop: session is cinnamon, establishing proxy Cjs-Message: 11:00:35.345: JS LOG: [LookingGlass/info] Adding XAppStatusIcon: blueberry (org.x.StatusIcon.PID-1981-0) cinnamon-session[1471]: WARNING: t+9,77932s: Detected that screensaver has appeared on the bus Cinnamon warning: Log level 128: posix_spawn avoided (fd close requested) Cjs-Message: 11:00:38.377: JS LOG: [LookingGlass/info] Adding XAppStatusIcon: slack (org.x.StatusIcon.PID-1765-0) Cjs-Message: 11:00:50.646: JS LOG: [LookingGlass/info] Adding XAppStatusIcon: mintUpdate.py (org.x.StatusIcon.PID-2103-0) /usr/lib/python3/dist-packages/mintcommon/installer/_flatpak.py:13: PyGIWarning: AppStreamGlib was imported without specifying a version first. Use gi.require_version('AppStreamGlib', '1.0') before import to ensure that the right version gets loaded. from gi.repository import AppStreamGlib, GLib, GObject, Gtk, Gio Cinnamon warning: Log level 128: posix_spawn avoided (fd close requested) Cjs-Message: 11:01:15.157: JS LOG: [LookingGlass/info] Adding XAppStatusIcon: mintreport (org.x.StatusIcon.PID-2446-0) Cinnamon warning: Log level 128: posix_spawn avoided (fd close requested) Cinnamon warning: Log level 128: posix_spawn avoided (fd close requested) Cinnamon warning: Window 0x7400007 (win0) sets an MWM hint indicating it isn't resizable, but sets min size 2 x 2 and max size 2147483647 x 2147483647; this doesn't make much sense.