vnc4server fails to launch awesome wm

[SNemiro]

Ubuntu 16.04
vnc4server 4.1.1+xorg4.3.0-37.3ubuntu2
awesome 3.5.6-1build1

xstartup:
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#!/bin/sh

xsetroot -solid grey
export XKL_XMODMAP_DISABLE=1
awesome
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when a vncserver is started, the WM fails to launch, showing the following output in the session log: (in this case, session 33)

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Xvnc Free Edition 4.1.1 - built Feb 25 2015 23:02:21
Copyright (C) 2002-2005 RealVNC Ltd.
See http://www.realvnc.com for information on VNC.
Underlying X server release 40300000, The XFree86 Project, Inc

Wed Nov 23 14:00:53 2016
 vncext: VNC extension running!
 vncext: Listening for VNC connections on port 5933
 vncext: created VNC server for screen 0
error opening security policy file /etc/X11/xserver/SecurityPolicy
Could not init font path element /usr/X11R6/lib/X11/fonts/Type1/, removing from list!
Could not init font path element /usr/X11R6/lib/X11/fonts/Speedo/, removing from list!
Could not init font path element /usr/X11R6/lib/X11/fonts/misc/, removing from list!
Could not init font path element /usr/X11R6/lib/X11/fonts/75dpi/, removing from list!
Could not init font path element /usr/X11R6/lib/X11/fonts/100dpi/, removing from list!
Could not init font path element /usr/share/fonts/X11/75dpi/, removing from list!
Could not init font path element /usr/share/fonts/X11/100dpi/, removing from list!
E: awesome: signal_fatal:256: signal 11, dumping backtrace
awesome(backtrace_get+0x54) [0x4271af]
awesome() [0x40cf2d]
/lib/x86_64-linux-gnu/libc.so.6(+0x354b0) [0x7feb4ee1d4b0]
awesome(screen_scan+0xa0) [0x421d55]
awesome(main+0x6bd) [0x40d8f9]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7feb4ee08830]
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It works OK under Ubuntu 14.04:
vnc4server 4.1.1+xorg4.3.0-37ubuntu5.0.2
awesome 3.4.15-1ubuntu1