diff --git a/addons/web/static/src/js/promise_extension.js b/addons/web/static/src/js/promise_extension.js
new file mode 100644
index 00000000000..4758975c712
--- /dev/null
+++ b/addons/web/static/src/js/promise_extension.js
@@ -0,0 +1,22 @@
+/**
+ * This file adds a 'guardedCatch' function to the Promise API. This function
+ * has to be used when we don't want to swallow real errors (crashes), like
+ * 'catch' does (i.e. basically all the time in Odoo). We only execute the
+ * 'onRejected' handler if the rejection's reason is not an Error, and we always
+ * return a rejected Promise to let the rejection bubble up (and trigger the
+ * 'unhandledrejection' event).
+ */
+
+(function () {
+    var _catch = Promise.prototype.catch;
+    Promise.prototype.guardedCatch = function (onRejected) {
+        return _catch.call(this, function (reason) {
+            if (!reason || !(reason instanceof Error)) {
+                if (onRejected) {
+                    onRejected.call(this, reason);
+                }
+            }
+            return Promise.reject(reason);
+        });
+    };
+})();
diff --git a/addons/web/static/src/js/services/crash_manager.js b/addons/web/static/src/js/services/crash_manager.js
index 31aa178dc1b..db88d688505 100644
--- a/addons/web/static/src/js/services/crash_manager.js
+++ b/addons/web/static/src/js/services/crash_manager.js
@@ -20,9 +20,29 @@ var map_title ={
 };
 
 var CrashManager = core.Class.extend({
-    init: function() {
+    init: function () {
+        var self = this;
         this.active = true;
         this.isConnected = true;
+
+        // listen to unhandled rejected promises, and throw an error when the
+        // promise has been rejected due to a crash
+        window.addEventListener('unhandledrejection', function (ev) {
+            if (ev.reason && ev.reason instanceof Error) {
+                var traceback = ev.reason.stack;
+                self.show_error({
+                    type: _t("Odoo Client Error"),
+                    message: '',
+                    data: {debug: _t('Traceback:') + "\n" + traceback},
+                });
+            } else {
+                // the rejection is not due to an Error, so prevent the browser
+                // from displaying an 'unhandledrejection' error in the console
+                ev.stopPropagation();
+                ev.stopImmediatePropagation();
+                ev.preventDefault();
+            }
+        });
     },
     enable: function () {
         this.active = true;
diff --git a/addons/web/views/webclient_templates.xml b/addons/web/views/webclient_templates.xml
index 5484db9294c..764084dd0ac 100644
--- a/addons/web/views/webclient_templates.xml
+++ b/addons/web/views/webclient_templates.xml
@@ -104,6 +104,7 @@
         <script type="text/javascript" src="/web/static/lib/clipboard/clipboard.js"></script>
 
         <script type="text/javascript" src="/web/static/lib/qweb/qweb2.js"></script>
+        <script type="text/javascript" src="/web/static/src/js/promise_extension.js"></script>
         <script type="text/javascript" src="/web/static/src/js/boot.js"></script>
         <script type="text/javascript" src="/web/static/src/js/libs/autocomplete.js"></script>
         <script type="text/javascript" src="/web/static/src/js/libs/bootstrap.js"></script>