WinCC V7.4 Web Navigator Edge IE Mode: Setup and Troubleshooting

Overview

Siemens WinCC V7.4 SP1 Web Navigator was engineered around the legacy Microsoft Internet Explorer (IE) ActiveX plug-in stack. The deprecation of the standalone IE11 desktop application and its removal from Windows 11 / Windows Server 2022 makes it impossible to launch the original WinCC Web Navigator plug-in with a normal browser shortcut. The supported path forward is the Chromium-based Microsoft Edge Internet Explorer Mode (IE Mode), which renders IE-only ActiveX controls inside a Chromium tab. This reference walks through the complete Edge-side configuration, the WinCC Web Navigator client installation, and the resolution of the two field-reported failure modes: a webnavigatorclient.exe installer that loops on a restart prompt, and a published client that is stuck on the Connecting screen.

Background: WinCC Web Navigator and the IE Retirement

Microsoft retired the Internet Explorer 11 desktop application on June 15, 2022, for most Windows 10 SKUs and removed the iexplore.exe binary entirely from Windows 11 22H2 and later. WinCC V7.4 SP1's Web Navigator client depends on the Microsoft WinCC WebNavigator ActiveX control, which uses the MSHTML (Trident) rendering engine plus signed ActiveX hosting. Edge IE Mode re-implements both behaviours inside a Chromium process:

• The MSHTML engine is loaded in-process as edge.exe --ie-mode for any URL listed in the Enterprise Mode Site List or opened from the ie-mode tab action.
• ActiveX hosting is supported only when the IE Mode tab is launched in the user's security context (not in a kiosk sandbox).
• The WinCCWebNavigatorClientSetup.exe (often called webnavigatorclient.exe in field notes) installs the cabinet-signed ActiveX and the WinCCViewerRT runtime components.

See the Siemens Knowledge Base article 109792981 — How do you operate the WinCC V7.4 SP1 WebNavigator with Microsoft Edge? for the vendor's official configuration sequence.

Prerequisites

Enable Microsoft Edge IE Mode (Single Workstation)

This is the manual sequence used when no Group Policy or Enterprise Site List is pushed from Active Directory.

1. Open Microsoft Edge and type edge://settings/defaultBrowser in the address bar.
2. Set Allow sites to be reloaded in Internet Explorer mode to Allow.
3. Choose Default under How to reload sites if you want Edge to auto-promote IE-mode-eligible pages; choose Don't allow and use the manual tab reload if you want explicit operator control.
4. Optionally set Let Internet Explorer open sites in Microsoft Edge to Always so legacy shortcuts redirect cleanly.
5. Close Edge completely (all windows, including the tray icon) and restart it.

Verify the setting persisted:

The toggle must report Allowed in red text. If it is greyed out, a Group Policy override is in effect — see the Enterprise Deployment section.

Add the WinCC Web Navigator URL to Trusted Sites

Edge IE Mode respects the same Windows Internet Options security zones that legacy IE used. The ActiveX installation step requires the URL to be in the Trusted Sites zone, and the runtime graphics plug-in will only initialise without a security prompt if the zone is trusted.

1. Open Edge and type edge://settings/clearBrowserData — skip the clearing step, the goal is just to enter a settings page.
2. From the Edge menu choose Settings → Cookies and site permissions → Pop-ups and redirects and confirm the WinCC server URL is not blocked.
3. Open Internet Options from the Windows Run dialog (inetcpl.cpl) or via Edge → Settings → Default browser → Internet Options.
4. Switch to the Security tab, select Trusted sites, and click Sites.
5. Uncheck Require server verification (https:) for all sites in this zone if the WinCC WebNavigator is published over plain HTTP.
6. Add the URL. Use the bare host for HTTP (http://winccsrv) or the FQDN for HTTPS (https://winccsrv.contoso.local). Wildcards (*.contoso.local) are supported.
7. Click Add → Close → OK.

Open the WinCC Web Navigator in Edge

1. Open a new tab in Edge and navigate to the Web Navigator URL, for example http://winccsrv/WebNavigator/ or the configured alias.
2. If the page loads in modern Edge rendering, click the three-dot menu on the tab and choose Reload in Internet Explorer mode. Alternatively, look for the small IE ring icon in the address bar's right side and click it to enter IE Mode.
3. When prompted by Edge, choose Open in Internet Explorer mode next time only if you want the URL persisted into the local edge://settings/defaultBrowser site list.
4. If you still get a blank or modern-rendered page, close the tab, reopen it with Ctrl+Shift+M disabled (do not use the mobile emulator), and retry.

The page should now display the WinCC Web Navigator login. The ActiveX bar at the top will request installation of WinCC Web Navigator Control if it is not yet present.

Install webnavigatorclient.exe

The full WinCC Web Navigator client runtime is installed by running WinCCWebNavigatorClientSetup.exe (sometimes referred to in field tickets as webnavigatorclient.exe). It installs:

• WinCCWebNavigatorControl.dll (signed ActiveX)
• WinCCViewerRT.exe and supporting runtime
• Registry keys under HKLM\SOFTWARE\Siemens\WinCC\Web Navigator\Client
• WinCC Web Navigator URL Handler for webnavigator://

Launch the installer elevated (right-click → Run as administrator) and follow the wizard. Accept the cabinet signing certificate if the UAC prompt appears. Restart the workstation at the end of the installer when prompted.

Issue 1: webnavigatorclient.exe Restart Loop

Symptom

The installer runs through its UI, reaches the end, and prompts for a restart. After the restart, launching the same installer starts over and prompts for a restart again. Repeating the cycle indefinitely does not clear the flag.

Root Cause

Windows Installer (MSI) records a Pending Reboot flag whenever a previous installer run completed a file-in-use rename, pending registry write, or service restart. WinCC's installer checks the standard reboot-flag registry locations; if any of them is set, it refuses to commit and re-arms the prompt.

Resolution

1. Stop the Windows Installer service: net stop msiserver from an elevated command prompt.
2. Stop the Windows Update service: net stop wuauserv.
3. Close all Edge, IE-mode, and Office processes. Check tasklist | findstr /i "wincc ie edge".
4. Back up and clear the registry keys listed above using reg delete or regedit. Example: reg delete "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired" /f.
5. Reboot the workstation cleanly. Do not skip — clearing PendingFileRenameOperations without a reboot leaves the file-rename queue in an undefined state.
6. Re-run WinCCWebNavigatorClientSetup.exe elevated.

Verification

After successful install, the following files must exist:

%ProgramFiles%\Siemens\Automation\WinCC Web Navigator\Client\WinCCWebNavigatorControl.dll
%ProgramFiles%\Siemens\Automation\WinCC Web Navigator\Client\WinCCViewerRT.exe

And the registry hive HKLM\SOFTWARE\Siemens\WinCC\Web Navigator\Client\InstallPath must point to the install folder.

Issue 2: Web Navigator Stuck on the Connecting Screen

Symptom

A workstation that previously opened the Web Navigator successfully now opens Edge, enters IE Mode, and the WinCC graphic window sits on the splash screen reading Connecting... indefinitely. No error message is displayed, and the progress indicator does not advance.

Root Cause Path

The Connecting splash is the client waiting for the WinCC Web Navigator server to complete its HTTP handshake and push the initial picture. The five typical failure points are listed below in order of frequency observed in the field.

Server-Side Checks

1. Open IIS Manager on the WinCC server. Expand Sites → Default Web Site and confirm the WebNavigator application is present and its application pool is started.
2. Right-click the application and choose Manage Application → Browse. The browser should display the WinCC Web Navigator landing page without errors.
3. From the WinCC Explorer, open Web Navigator → Diagnostics and review the published graphic count. Zero pictures published means the publisher configuration was reset.
4. Verify the WinCC WebNavigator service is set to Automatic (Delayed Start) and currently in Running state. Restart with net stop "WinCC WebNavigator" & net start "WinCC WebNavigator".

Client-Side Checks

1. Disable the Edge extension IE Mode Helper if installed — third-party extensions occasionally intercept the IE-mode tab launch and break the ActiveX host.
2. Open edge://flags and ensure Enable IE Mode is set to Default (not Disabled).
3. Launch the URL with the --ie-mode-test Edge flag: msedge.exe --ie-mode --ie-mode-test=http://winccsrv/WebNavigator/. If the test page loads, the URL is recognised as IE-mode-eligible.
4. If still stuck, run WinCCViewerRT.exe /server:winccsrv directly from %ProgramFiles%\Siemens\Automation\WinCC Web Navigator\Client. If the standalone runtime opens the picture, the IE Mode ActiveX host is at fault; if not, the server itself is unreachable.

Alternative: WinCCViewerRT.exe

When IE Mode is blocked by the operating system or by tenant policy, the supported fallback is the WinCCViewerRT.exe runtime. It is part of the same WinCC Web Navigator client install and bypasses the browser entirely:

• Standalone executable — no IE Mode, no Chromium Edge, no third-party browser.
• Reads the published Web Navigator configuration directly over TCP port 80 / 443.
• Supports command-line startup for kiosk boot scenarios: WinCCViewerRT.exe /server:winccsrv /project:Plant1 /autostart.
• Independent of Edge version, Windows 11 24H2, or any browser retirement.

For greenfield deployments on Windows 11 23H2 and later, plan the runtime station with WinCCViewerRT.exe as the primary and Edge IE Mode only as the engineering / supervisor browser. This avoids any future browser-engine compatibility regressions.

Enterprise Deployment via Group Policy

For multi-site fleets, push the IE Mode configuration centrally using the Microsoft Edge Administrative Templates (MicrosoftEdge.admx) and an Enterprise Mode Site List XML.

1. Download the latest Microsoft Edge for Business policy template.
2. Copy msedge.admx and msedge.adml into %SystemRoot%\PolicyDefinitions on a Windows DC.
3. In Computer Configuration → Administrative Templates → Microsoft Edge, configure:

4. Publish the site list, example content:

<?xml version="1.0" encoding="UTF-8"?>
<site-list version="2">
  <site url="http://winccsrv/WebNavigator/">
    <compat-mode>IE11</compat-mode>
    <open-in>IE11</open-in>
  </site>
  <site url="http://winccsrv">
    <compat-mode>IE11</compat-mode>
    <open-in>IE11</open-in>
  </site>
</site-list>

5. Force a Group Policy refresh: gpupdate /force on the target workstation.
6. Restart Edge and verify edge://compat/enterprise shows the WinCC server URLs as IE Mode.

Verification Checklist

Troubleshooting Matrix

FAQ