Edge driver unable to connect to WebView2 instance

[JamesHMcKay]

Hello,

We have been using WebView2 in a C++ application and performing automated tests using the Edge Driver via Selenium for the last year. However, in recent versions of the Edge runtime the driver is unable to connect.

I have created a minimal example that reproduces the issue.

Environment

• Selenium 4.19.0
• Edge driver 123.0.2420.65
• WebView2 Runtime 123.0.2420.65

The environment variable WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS is set to the value --enable-features=msEdgeDevToolsWdpRemoteDebugging --remote-debugging-port=9224.

Minimal example code

The following is the Win32 C++ app that reproduces this, it is a very stripped down version from the official tutorial.

// compile with: /D_UNICODE /DUNICODE /DWIN32 /D_WINDOWS /c
#include <windows.h>
#include <stdlib.h>
#include <string>
#include <tchar.h>
#include <wrl.h>
#include <wil/com.h>
#include "WebView2.h"

using namespace Microsoft::WRL;

static TCHAR szWindowClass[] = _T("WebViewApp");
static TCHAR szTitle[] = _T("WebView App");
HINSTANCE hInst;
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
static wil::com_ptr<ICoreWebView2Controller> webviewController;
static wil::com_ptr<ICoreWebView2> webview;

HRESULT InitWebView2(ICoreWebView2Controller* controller, HWND hWnd)
{
    if (controller != nullptr) {
        webviewController = controller;
        webviewController->get_CoreWebView2(&webview);
    }

    wil::com_ptr<ICoreWebView2Settings> settings;
    webview->get_Settings(&settings);
    settings->put_IsScriptEnabled(TRUE);
    settings->put_AreDefaultScriptDialogsEnabled(TRUE);
    settings->put_IsWebMessageEnabled(TRUE);

    RECT bounds;
    GetClientRect(hWnd, &bounds);
    webviewController->put_Bounds(bounds);

    webview->Navigate(L"https://www.bing.com/");

    return S_OK;
}

int CALLBACK WinMain(
    _In_ HINSTANCE hInstance,
    _In_ HINSTANCE hPrevInstance,
    _In_ LPSTR     lpCmdLine,
    _In_ int       nCmdShow
)
{
    WNDCLASSEX wcex{};

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
    wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = nullptr;
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance, IDI_APPLICATION);

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(nullptr, _T("Call to RegisterClassEx failed!"), _T("WebView App"), NULL);
        return 1;
    }

    hInst = hInstance;
    HWND hWnd = CreateWindow(
        szWindowClass,
        szTitle,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        1200, 900,
        nullptr,
        nullptr,
        hInstance,
        nullptr
    );

    if (!hWnd)
    {
        MessageBox(nullptr, _T("Call to CreateWindow failed!"), _T("WebView App"), NULL);
        return 1;
    }

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    CreateCoreWebView2EnvironmentWithOptions(nullptr, nullptr, nullptr,
        Callback<ICoreWebView2CreateCoreWebView2EnvironmentCompletedHandler>(
            [hWnd](HRESULT, ICoreWebView2Environment* env) {
                env->CreateCoreWebView2Controller(hWnd, Callback<ICoreWebView2CreateCoreWebView2ControllerCompletedHandler>(
                    [hWnd](HRESULT, ICoreWebView2Controller* controller) {
                        return InitWebView2(controller, hWnd);
                    }).Get());
                return S_OK;
            }).Get());

    MSG msg;
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_SIZE:
        if (webviewController != nullptr) {
            RECT bounds;
            GetClientRect(hWnd, &bounds);
            webviewController->put_Bounds(bounds);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }

    return 0;
}

The Python code to load up the driver that gives us the error is:

from selenium import webdriver
from selenium.webdriver.edge.options import Options

options = Options()
options.debugger_address = "localhost:9224"

driver = webdriver.Edge(options) # error is raised on this line

The error message

selenium.common.exceptions.WebDriverException: Message: disconnected: not connected to DevTools
  (failed to check if window was closed: disconnected: not connected to DevTools)
  (Session info: MicrosoftEdge=123.0.2420.65)
Stacktrace:
        GetHandleVerifier [0x01097A13+230547]
        Microsoft::Applications::Events::time_ticks_t::time_ticks_t [0x00F73BD1+400897]
        Microsoft::Applications::Events::ILogConfiguration::operator* [0x00D86070+3568]
        Microsoft::Applications::Events::ILogConfiguration::GetModules [0x00D7718B+6219]
        Microsoft::Applications::Events::ILogConfiguration::GetModules [0x00D77EFD+9661]
        Microsoft::Applications::Events::ILogConfiguration::operator* [0x00D86475+4597]
        Microsoft::Applications::Events::IAuthTokensController::~IAuthTokensController [0x00D6E413+48067]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DD88A0+234656]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DD805C+232540]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DCEB86+194438]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DB2533+78131]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DB1515+74005]
        Microsoft::Applications::Events::GUID_t::GUID_t [0x00DB1F3D+76605]
        GetHandleVerifier [0x011898DC+1221468]
        Microsoft::Applications::Events::FromJSON [0x0125A502+132370]
        Microsoft::Applications::Events::FromJSON [0x01259E87+130711]
        Microsoft::Applications::Events::FromJSON [0x0124ECF0+85248]
        Microsoft::Applications::Events::FromJSON [0x0125AEDB+134891]
        Microsoft::Applications::Events::time_ticks_t::time_ticks_t [0x00F86A9F+478415]
        Microsoft::Applications::Events::time_ticks_t::time_ticks_t [0x00F7C5B8+436200]
        Microsoft::Applications::Events::time_ticks_t::time_ticks_t [0x00F7C72B+436571]
        Microsoft::Applications::Events::time_ticks_t::time_ticks_t [0x00F66DB4+348132]
        BaseThreadInitThunk [0x76AE7BA9+25]
        RtlInitializeExceptionChain [0x77D8BDAB+107]
        RtlClearBits [0x77D8BD2F+191]

If I shut down the webview2 application then the script runs without error, so we can use it to control the Edge browser for example. The issue seems to only occur if a webview2 application is running.

Question

This setup used to work well with older versions and is still working on our CI where we have version 119 of the runtime. So we are hoping to understand if there has been a change in the interface that we need to account for in the way we are doing this, or if there is a bug in the latest versions of the webview2 runtime that could be causing this?

Thanks for your help!

[victorhuangwq]

Are you still facing this issue?

[JamesHMcKay]

Yes absolutely. Tried it again on a version about a week or so ago and it was failing even worse now, it will give the same error now even if I don't have a webview2 application open.