I installed Ubuntu 18.04 minimal, and then Chromium via Ubuntu Software (used snap).
The 1st session was OK.
The next time I tried to start Chromium it did not work.
dmesg output below...
[ 16.281404] audit: type=1400 audit(1525020432.644:2): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/bin/man" pid=814 comm="apparmor_parser"
[ 16.281409] audit: type=1400 audit(1525020432.644:3): apparmor="STATUS" operation="profile_load" profile="unconfined" name="man_filter" pid=814 comm="apparmor_parser"
[ 16.281412] audit: type=1400 audit(1525020432.644:4): apparmor="STATUS" operation="profile_load" profile="unconfined" name="man_groff" pid=814 comm="apparmor_parser"
[ 16.282542] audit: type=1400 audit(1525020432.644:5): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/snap/core/4486/usr/lib/snapd/snap-confine" pid=811 comm="apparmor_parser"
[ 16.282547] audit: type=1400 audit(1525020432.644:6): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/snap/core/4486/usr/lib/snapd/snap-confine//mount-namespace-capture-helper" pid=811 comm="apparmor_parser"
[ 16.301350] audit: type=1400 audit(1525020432.664:7): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/cups-browsed" pid=816 comm="apparmor_parser"
[ 16.303129] audit: type=1400 audit(1525020432.664:8): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/sbin/dhclient" pid=810 comm="apparmor_parser"
[ 16.303135] audit: type=1400 audit(1525020432.664:9): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=810 comm="apparmor_parser"
[ 16.303139] audit: type=1400 audit(1525020432.664:10): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/NetworkManager/nm-dhcp-helper" pid=810 comm="apparmor_parser"
[ 16.303142] audit: type=1400 audit(1525020432.664:11): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/connman/scripts/dhclient-script" pid=810 comm="apparmor_parser"
[ 23.838673] IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready
[ 23.853369] r8169 0000:03:00.0 enp3s0: link down
[ 23.853475] IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready
[ 26.585485] r8169 0000:03:00.0 enp3s0: link up
[ 26.585498] IPv6: ADDRCONF(NETDEV_CHANGE): enp3s0: link becomes ready
[ 28.699891] kauditd_printk_skb: 30 callbacks suppressed
[ 28.699893] audit: type=1400 audit(1525020445.060:42): apparmor="DENIED" operation="capable" profile="/usr/lib/snapd/snap-confine" pid=1061 comm="snap-confine" capability=2 capname="dac_read_search"
[ 66.600752] rfkill: input handler disabled
[ 90.129998] audit: type=1107 audit(1525034906.353:43): pid=907 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call" bus="system" path="/" interface="org.freedesktop.DBus.ObjectManager" member="GetManagedObjects" mask="send" name="org.bluez" pid=2308 label="snap.chromium.chromium"
exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
[ 216.710536] audit: type=1107 audit(1525035032.932:44): pid=907 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call" bus="system" path="/" interface="org.freedesktop.DBus.ObjectManager" member="GetManagedObjects" mask="send" name="org.bluez" pid=2856 label="snap.chromium.chromium"
exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
[ 236.815748] audit: type=1400 audit(1525035053.036:45): apparmor="DENIED" operation="ptrace" profile="snap.chromium.chromium" pid=2856 comm="chromium-browse" requested_mask="trace" denied_mask="trace" peer="unconfined"
[ 348.745271] audit: type=1107 audit(1525035164.968:46): pid=907 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call" bus="system" path="/" interface="org.freedesktop.DBus.ObjectManager" member="GetManagedObjects" mask="send" name="org.bluez" pid=3530 label="snap.chromium.chromium"
exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
[ 368.871445] audit: type=1400 audit(1525035185.097:47): apparmor="DENIED" operation="ptrace" profile="snap.chromium.chromium" pid=3530 comm="chromium-browse" requested_mask="trace" denied_mask="trace" peer="unconfined"
[ 382.640426] audit: type=1107 audit(1525035198.865:48): pid=907 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call" bus="system" path="/" interface="org.freedesktop.DBus.ObjectManager" member="GetManagedObjects" mask="send" name="org.bluez" pid=3756 label="snap.chromium.chromium"
exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: apparmor 2.12-4ubuntu5
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Apr 29 17:12:14 2018
InstallationDate: Installed on 2018-04-28 (1 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcKernelCmdline: BOOT_IMAGE=/boot/vmlinuz-4.15.0-20-generic root=UUID=b88709ac-8c8f-4c78-bbd9-f433d1bd6ee5 ro quiet splash vt.handoff=1
SourcePackage: apparmor
UpgradeStatus: No upgrade log present (probably fresh install)
Status changed to 'Confirmed' because the bug affects multiple users.