I am having the same problem with webbrowser-app. My machine : 
Lenovo ThinkPad X230
Memory : 7,5GiB
Processor : Intel® Core™ i5-3320M CPU @ 2.60GHz × 4
Graphics : Intel® Ivybridge Mobile 
OS Type : Ubuntu 16.04LTS 64bit
Disk : 228,0GB SSD

I used to use "webbrowser" to work under WordPress because some functionalities are no more operational with Chrome; For couple of months now I can't use "webbrowser". I tried to uninstall it, reinstall it, no way!

PS : I am not an Ubuntu specialist but a basic user who doesn't want to deal anymore with MicroSoft Windows ...

here is my log in terminal when I input webbrowser-app, if this may help : 

joel-pol@JPS-X230:~$ webbrowser-app

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.
libGL error: MESA-LOADER: failed to retrieve device information
libGL error: Version 4 or later of flush extension not found
libGL error: failed to load driver: i915
libGL error: MESA-LOADER: failed to retrieve device information
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
unity::action::ActionManager::ActionManager(QObject*):
	Could not determine application identifier. HUD will not work properly.
	Provide your application identifier in $APP_ID environment variable.
UCUriHandler: Empty "APP_ID" environment variable, ignoring.
file:///usr/share/webbrowser-app/webbrowser/ContentPickerDialog.qml:22:1: module "Ubuntu.Content" is not installed
file:///usr/share/webbrowser-app/webbrowser/ContentDownloadDialog.qml:22:1: module "Ubuntu.Content" is not installed
file:///usr/share/webbrowser-app/ContentHandler.qml:20:1: module "Ubuntu.Content" is not installed
file:///usr/share/webbrowser-app/webbrowser/DownloadHandler.qml:20:1: module "Ubuntu.DownloadManager" is not installed

(webbrowser-app:22269): IBUS-WARNING **: Unable to connect to ibus: Could not connect: Permission denied
QNetworkManagerInterface::QNetworkManagerInterface(QObject*) propsReply "An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.179\" (uid=1000 pid=22269 comm=\"webbrowser-app \") interface=\"org.freedesktop.DBus.Properties\" member=\"GetAll\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.freedesktop.NetworkManager\" (uid=0 pid=1063 comm=\"/usr/sbin/NetworkManager --no-daemon \")"
QNetworkManagerInterface::QNetworkManagerInterface(QObject*) nmReply "An AppArmor policy prevents this sender from sending this message to this recipient; type=\"method_call\", sender=\":1.179\" (uid=1000 pid=22269 comm=\"webbrowser-app \") interface=\"org.freedesktop.NetworkManager\" member=\"GetDevices\" error name=\"(unset)\" requested_reply=\"0\" destination=\"org.freedesktop.NetworkManager\" (uid=0 pid=1063 comm=\"/usr/sbin/NetworkManager --no-daemon \")"
"Object path cannot be empty"
libGL error: MESA-LOADER: failed to retrieve device information
libGL error: Version 4 or later of flush extension not found
libGL error: failed to load driver: i915
libGL error: MESA-LOADER: failed to retrieve device information
shm_open() failed: Permission denied

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.

(webbrowser-app:22269): dconf-CRITICAL **: unable to create file '/run/user/1000/dconf/user': Permission denied.  dconf will not work properly.
[0929/155756.261693:ERROR:child_thread_impl.cc(762)] Request for unknown Channel-associated interface: ui::mojom::GpuMain
TouchSelectionController::active is deprecated, use TouchSelectionController::status instead
qml: Loaded 8 UA override(s) from file:///usr/lib/x86_64-linux-gnu/qt5/qml/Ubuntu/Web/ua-overrides-mobile.js
OxideQQuickWebView: canGoForward is deprecated. Please use the API provided by OxideQQuickNavigationHistory instead
OxideQQuickWebView: canGoBack is deprecated. Please use the API provided by OxideQQuickNavigationHistory instead
QOpenGLShader: could not create shader
intel_do_flush_locked failed: Invalid argument
[0929/155756.367295:FATAL:oxide_browser_process_main.cc(472)] Check failed: state_ == STATE_NOT_STARTED || state_ == STATE_SHUTDOWN. BrowserProcessMain::Shutdown() should be called before process exit
#0 0x7fe32f5dc63e <unknown>
#1 0x7fe32f5f637e <unknown>
#2 0x7fe330c17579 <unknown>
#3 0x7fe368a6bff8 <unknown>
#4 0x7fe368a6c045 exit
#5 0x7fe35260468e <unknown>
#6 0x7fe35260a55c <unknown>
#7 0x7fe35260a729 <unknown>
#8 0x7fe35260ff0b <unknown>
#9 0x7fe3523f3e7c <unknown>
#10 0x7fe35261124a <unknown>
#11 0x7fe3523e401b <unknown>
#12 0x7fe3523e4286 <unknown>
#13 0x7fe3523e4688 <unknown>
#14 0x7fe36a3a4d16 QOpenGLTextureGlyphCache::fillTexture()
#15 0x7fe36a330fc1 QTextureGlyphCache::fillInPendingGlyphs()
#16 0x7fe36aa61db7 <unknown>
#17 0x7fe36aa5fc4c <unknown>
#18 0x7fe36aae9677 <unknown>
#19 0x7fe36aaeda9c <unknown>
#20 0x7fe36aaea547 <unknown>
#21 0x7fe36aae8cb8 QQuickText::updatePaintNode()
#22 0x7fe36aaa72d8 QQuickWindowPrivate::updateDirtyNode()
#23 0x7fe36aaa7b4b QQuickWindowPrivate::updateDirtyNodes()
#24 0x7fe36aaa7cc0 QQuickWindowPrivate::syncSceneGraph()
#25 0x7fe36aa7612c <unknown>
#26 0x7fe36aa77aa6 <unknown>
#27 0x7fe36a0972b5 QWindow::event()
#28 0x7fe36aab1871 QQuickWindow::event()
#29 0x7fe36ae3b05c QApplicationPrivate::notify_helper()
#30 0x7fe36ae40516 QApplication::notify()
#31 0x7fe36992338b QCoreApplication::notifyInternal()
#32 0x7fe36a08f4ac QGuiApplicationPrivate::processExposeEvent()
#33 0x7fe36a09021d QGuiApplicationPrivate::processWindowSystemEvent()
#34 0x7fe36a073f08 QWindowSystemInterface::sendWindowSystemEvents()
#35 0x7fe36183a200 <unknown>
#36 0x7fe3682fb197 g_main_context_dispatch
#37 0x7fe3682fb3f0 <unknown>
#38 0x7fe3682fb49c g_main_context_iteration
#39 0x7fe3699797cf QEventDispatcherGlib::processEvents()
#40 0x7fe369920b4a QEventLoop::exec()
#41 0x7fe369928bec QCoreApplication::exec()
#42 0x55ed6bbbfe16 (/usr/bin/webbrowser-app+0x55ed6bbbfe15)
#43 0x55ed6bbb4a05 (/usr/bin/webbrowser-app+0x55ed6bbb4a04)
#44 0x7fe368a52830 __libc_start_main
#45 0x55ed6bbb4b69 (/usr/bin/webbrowser-app+0x55ed6bbb4b68)

Aborted (core dumped)
joel-pol@JPS-X230:~$