not supported scenario

src/app/accounts/accountsLoginController.js

@@ -90,10 +90,19 @@ angular
             for (var i = 0; i < keys.length; i++) {
                 var provider = $filter('filter')(constants.twoFactorProviderInfo, { type: keys[i], active: true });
                 if (provider.length && provider[0].priority > providerPriority) {
+                    if (provider[0].type === constants.twoFactorProvider.u2f && !u2f.isSupported) {
+                        continue;
+                    }
+
                     providerType = provider[0].type;
                     providerPriority = provider[0].priority;
                 }
             }
+
+            if (providerType === null) {
+                return null;
+            }
+
             return parseInt(providerType);
         }
 

src/app/accounts/accountsTwoFactorMethodsController.js

@@ -18,7 +18,7 @@
         if (providers.hasOwnProperty(constants.twoFactorProvider.duo)) {
             add(constants.twoFactorProvider.duo);
         }
-        if (providers.hasOwnProperty(constants.twoFactorProvider.u2f)) {
+        if (providers.hasOwnProperty(constants.twoFactorProvider.u2f) && u2f.isSupported) {
             add(constants.twoFactorProvider.u2f);
         }
 

src/app/accounts/views/accountsLoginTwoFactor.html

@@ -143,6 +143,15 @@
     </form>
 </div>
 
+<div ng-if="twoFactorProvider === null">
+    <p>
+        This account has two-factor login enabled, however, none of the configured two-factor providers are supported by this
+        web browser.
+    </p>
+    Please use a supported web browser (such as Chrome) and/or add additional providers that are better supported
+    across web browsers (such as an Authenticator App).
+</div>
+
 <hr />
 <ul>
     <li>

src/js/u2f-api.js

@@ -22,7 +22,7 @@ var u2f = u2f || {};
  * Modification:
  * Check if browser supports U2F API before this wrapper was added.
  */
-u2f.isSupported = ((typeof u2f !== 'undefined') && u2f.register) || (chrome && chrome.runtime);
+u2f.isSupported = !!(((typeof u2f !== 'undefined') && u2f.register) || (chrome && chrome.runtime));
 
 /**
  * FIDO U2F Javascript API Version