diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
index e05e646..bb07677 100644
--- a/Source/WebKit/ChangeLog
+++ b/Source/WebKit/ChangeLog
@@ -1,5 +1,16 @@
 2019-10-15  Carlos Garcia Campos  <cgarcia@igalia.com>
 
+        Unreviewed. Fix several GTK tests in /WebKit2Gtk/TestUIClient crashing since r241988
+
+        Show a warning message and return nullptr from WebKitWebView::create if the new web view is not related to the
+        given one. Also make it clear in the documentation that the new web view should be related to the given one.
+
+        * UIProcess/API/glib/WebKitWebView.cpp:
+        (webkit_web_view_class_init):
+        (webkitWebViewCreateNewPage):
+
+2019-10-15  Carlos Garcia Campos  <cgarcia@igalia.com>
+
         Unreviewed. Fix GTK test /webkit/Authentication/authentication-storage after r249962
 
         * UIProcess/API/glib/WebKitWebView.cpp:
diff --git a/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp b/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp
index 4278f22..c3b5c9c 100644
--- a/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp
+++ b/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp
@@ -1353,10 +1353,8 @@
      * The #WebKitNavigationAction parameter contains information about the
      * navigation action that triggered this signal.
      *
-     * When using %WEBKIT_PROCESS_MODEL_MULTIPLE_SECONDARY_PROCESSES
-     * process model, the new #WebKitWebView should be related to
-     * @web_view to share the same web process, see webkit_web_view_new_with_related_view()
-     * for more details.
+     * The new #WebKitWebView must be related to @web_view, see
+     * webkit_web_view_new_with_related_view() for more details.
      *
      * The new #WebKitWebView should not be displayed to the user
      * until the #WebKitWebView::ready-to-show signal is emitted.
@@ -2216,7 +2214,12 @@
     WebKitWebView* newWebView;
     g_signal_emit(webView, signals[CREATE], 0, navigationAction, &newWebView);
     if (!newWebView)
-        return 0;
+        return nullptr;
+
+    if (&getPage(webView).process() != &getPage(newWebView).process()) {
+        g_warning("WebKitWebView returned by WebKitWebView::create signal was not created with the related WebKitWebView");
+        return nullptr;
+    }
 
     webkitWindowPropertiesUpdateFromWebWindowFeatures(newWebView->priv->windowProperties.get(), windowFeatures);
 
diff --git a/Tools/ChangeLog b/Tools/ChangeLog
index e656046..deb8e6a 100644
--- a/Tools/ChangeLog
+++ b/Tools/ChangeLog
@@ -1,5 +1,17 @@
 2019-10-15  Carlos Garcia Campos  <cgarcia@igalia.com>
 
+        Unreviewed. Fix several GTK tests in /WebKit2Gtk/TestUIClient crashing since r241988
+
+        This was not caused by r241988, but revealed the existing bug. We were not creating the new WebKitWebView in
+        UIClientTest with the related WebKitWebView. Since r241988, the new WebPageProxy drawing area is passed to
+        creationParameters(), but it's nullptr because the WebPageProxy hasn't been initialized yet. When using related
+        views, the new WebPageProxy is already initialized because it has running processes on creation.
+
+        * TestWebKitAPI/Tests/WebKitGLib/TestUIClient.cpp:
+        (testWebViewCreateNavigationData):
+
+2019-10-15  Carlos Garcia Campos  <cgarcia@igalia.com>
+
         Unreviewed. Fix GTK test /WebKit2Gtk/TestWebViewEditor
 
         It's failing since we delay the web process launch until the first load. Load about:blank in the test
diff --git a/Tools/TestWebKitAPI/Tests/WebKitGLib/TestUIClient.cpp b/Tools/TestWebKitAPI/Tests/WebKitGLib/TestUIClient.cpp
index 9c4074c..eb1bd3a 100644
--- a/Tools/TestWebKitAPI/Tests/WebKitGLib/TestUIClient.cpp
+++ b/Tools/TestWebKitAPI/Tests/WebKitGLib/TestUIClient.cpp
@@ -330,7 +330,7 @@
         g_assert_true(webView == m_webView);
         g_assert_nonnull(navigation);
 
-        auto* newWebView = Test::createWebView(webkit_web_view_get_context(webView));
+        auto* newWebView = Test::createWebView(webView);
 #if PLATFORM(GTK)
         g_object_ref_sink(newWebView);
 #endif
@@ -479,7 +479,7 @@
     test->loadHTML("<html><body onLoad=\"window.open();\"></html>");
     test->waitUntilMainLoopFinishes();
 
-    g_assert_cmpstr(webkit_uri_request_get_uri(webkit_navigation_action_get_request(test->m_navigation)), ==, "about:blank");
+    g_assert_cmpstr(webkit_uri_request_get_uri(webkit_navigation_action_get_request(test->m_navigation)), ==, "");
     g_assert_cmpuint(webkit_navigation_action_get_navigation_type(test->m_navigation), ==, WEBKIT_NAVIGATION_TYPE_OTHER);
     g_assert_cmpuint(webkit_navigation_action_get_mouse_button(test->m_navigation), ==, 0);
     g_assert_cmpuint(webkit_navigation_action_get_modifiers(test->m_navigation), ==, 0);