Created attachment 128518 [details]
X server log

After upgrading from 2:1.18.4-2 to 2:1.19.0-2 (Debian package versions), the X.org server has started to crash when switching virtual desktops - three times so far, in a space of 96 hours. Not all virtual desktop switches make the server crash, but all crashes have occurred as a result of switching virtual desktops.

These are the last lines in the log file (attached):

[ 56715.230] (EE) 
[ 56715.234] (EE) Backtrace:
[ 56715.250] (EE) 0: /usr/lib/xorg/Xorg (xorg_backtrace+0x4a) [0x564fb7ddcfea]
[ 56715.250] (EE) 1: /usr/lib/xorg/Xorg (0x564fb7c24000+0x1bcd69) [0x564fb7de0d6
9]
[ 56715.250] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7fbe5f96d000+0x111
00) [0x7fbe5f97e100]
[ 56715.250] (EE) 3: /usr/lib/x86_64-linux-gnu/libpixman-1.so.0 (pixman_region_u
nion+0x2e) [0x7fbe60948a7e]
[ 56715.250] (EE) 4: /usr/lib/xorg/Xorg (0x564fb7c24000+0x13eb60) [0x564fb7d62b6
0]
[ 56715.250] (EE) 5: /usr/lib/xorg/Xorg (0x564fb7c24000+0x142215) [0x564fb7d6621
5]
[ 56715.250] (EE) 6: /usr/lib/xorg/Xorg (0x564fb7c24000+0xf2240) [0x564fb7d16240]
[ 56715.250] (EE) 7: /usr/lib/xorg/Xorg (0x564fb7c24000+0xf3a95) [0x564fb7d17a95]
[ 56715.250] (EE) 8: /usr/lib/xorg/Xorg (0x564fb7c24000+0x544c5) [0x564fb7c784c5]
[ 56715.250] (EE) 9: /usr/lib/xorg/Xorg (0x564fb7c24000+0x58448) [0x564fb7c7c448]
[ 56715.250] (EE) 10: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf1) [0x7fbe5f5ef2b1]
[ 56715.250] (EE) 11: /usr/lib/xorg/Xorg (_start+0x2a) [0x564fb7c6613a]
[ 56715.250] (EE) 
[ 56715.250] (EE) Segmentation fault at address 0xa
[ 56715.250] (EE) 
Fatal server error:
[ 56715.250] (EE) Caught signal 11 (Segmentation fault). Server aborting
[ 56715.250] (EE) 
[ 56715.250] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
[ 56715.250] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 56715.250] (EE) 
[ 56715.250] (II) AIGLX: Suspending AIGLX clients for VT switch
[ 56715.308] (EE) Server terminated with error (1). Closing log file.