What it seems to occur for me is that xfce4-session crashes at logout (and sometimes during a session) after upgrading to glib 2.36
Reverting to glib 2.34 solves the problem. I don't know if this is a glib or xfce4 bug.

Maybe related to this:

http://xfce.10915.n7.nabble.com/Bug-9709-New-periodic-crashes-of-xfce4-session-td41191.html#a41688

("The problem was definitely caused by various os/distributions upgrading their glib version to 2.36, and the crashes are a consequence of this")

Examples of crash:

Apr 24 00:49:02 parsec kernel: [ 29.353774] xfce4-session[634]: segfault at ffffffff00000000 ip 00007f123876f537 sp 00007fffe9447320 error 5 in libglib-2.0.so.0.3600.1[7f123870c000+fc000]
Apr 24 00:49:16 parsec kernel: [ 43.350057] xfce4-session[784]: segfault at ffffffff00000000 ip 00007f48fa747537 sp 00007ffff44dcaf0 error 5 in libglib-2.0.so.0.3600.1[7f48fa6e4000+fc000]

@cgarcia: glib2 2.36.1-2 should behave better in that regard (that issue is tracked in  FS#34630 ).

As for OP's issue, logging out works fine for me and the report lacks any useful information to try and reproduce it. (e.g. did this start happening after a system upgrade or is it a fresh installation; are there any clues in the journal; does it happen on every log out or only some of the time; etc ...)

I use Slim as Desktop-independent graphical login manager for X11, version 1.3.5-2. This happened with the last 2 updates. I update Arch every day so I don't remember what has been updated exactly.

You can try grabbing glib2 2.36.1-2 from [testing] and see if that solves your issue.

@cgarcia I have the same problem, this crash appears when i click action buttons on my xfce panel (for, logout/shutdown/reboot...) or in other actions.

my dmesg:
[ 1553.318851] xfce4-session[1068]: segfault at ffffffff00000000 ip 00007fd8e7a63537 sp 00007fffe260a3e0 error 5 in libglib-2.0.so.0.3600.1[7fd8e7a00000+fc000]
[ 1553.835181] traps: xfce4-power-man[1133] general protection ip:7f9605af1377 sp:7fff829a3d30 error:0 in libSM.so.6.0.1[7f9605aef000+7000]
[ 1553.868121] xfsettingsd[1084]: segfault at 4 ip 00007faf9fda05b0 sp 00007fffa8b32860 error 6 in libSM.so.6.0.1[7faf9fd9e000+7000]

@foutrelis I have upgraded glib2 from testing but doesn't solve my problem

I forgot to say that this happen on ArchLinux 64 bit version.

If you're having troubles with xfce4-session segfaulting, there seem to be a fix upstream: https://bugzilla.xfce.org/show_bug.cgi?id=9709
Just install xfce4-session-git from aur.

This is not related with this bug.

I have updated glib2 to version 2.36.1-3. The segfault bug seems to be fixed in this version. I am still conducting more tests to verify it.

Last ArchLinux update fixed this bug. You can cloase it.