WebNavigator Client 6.1a Fails to Load on Internet Explorer 11 — Root Cause and Verified Workarounds

Siemens WinCC WebNavigator Client V6.1a is a well-documented component of the WinCC V6.x SCADA stack and was originally qualified against Microsoft Internet Explorer 6 and 8. When the same client is launched on Internet Explorer 11 (IE11), the ActiveX container either refuses to instantiate the WebNavigator control, returns silent script errors, or displays a blank picture area. The problem is not a configuration defect on the operator station; it is a release qualification gap. This reference explains the underlying cause, lists every configuration the user typically tries, and provides the two field-proven remediations (WinCCViewerRT substitution and upgrade to WebNavigator V7.4 or later) along with verification procedures.

1. Problem Summary

2. Affected Products and Version Range

The issue is specific to the WebNavigator Client delivered with the WinCC V6.0 / V6.1 / V6.2 releases and the Internet Explorer 11 browser engine. The WebNavigator component relies on the Microsoft ActiveX model, the legacy MSHTML document mode, and a set of COM objects (CCActiveX, WebNavCtl, WebNavX) that were compiled and digitally signed against the pre-IE10 rendering stack.

• WebNavigator Server: V6.0, V6.0 SP1, V6.1, V6.1a, V6.2, V6.2 SP1, V6.2 SP2
• WebNavigator Client: any build matching the server above (the client is installed by the WebNavigator Client setup from the same WinCC DVD/image)
• Browser engines that work: Internet Explorer 6, 7, 8 (IE8 confirmed by the original report; IE9 limited; IE10 limited)
• Browser engines that fail: Internet Explorer 11 in any document mode (Quirks, IE7 Standards, IE8 Standards, IE9 Standards, IE10 Standards, IE11 Edge)
• Browser engines that have no path forward on V6.x: Microsoft Edge (legacy EdgeHTML and Chromium), Chrome, Firefox, Safari — WebNavigator V6.x is ActiveX-only and cannot be ported

3. Root Cause Analysis

Three independent technical reasons converge to make the V6.1a client inoperable on IE11:

3.1 ActiveX hardening changes shipped with IE10 and IE11

Starting with IE10, Microsoft tightened the ActiveX initialization rules: per-site ActiveX initialization, out-of-date ActiveX blocking, and a hardened kill-bit list. WebNavigator V6.x ships an ActiveX control whose manifest does not declare a compatibility GUID recognized by the IE11 protected-mode loader, so the control is rejected before its IObjectWithSite::SetSite callback fires.

2.2 Document mode default in IE11

IE11 ignores legacy X-UA-Compatible meta tags in some enterprise configurations and defaults to the IE11 Edge document mode. The V6.1a client page was authored against the IE8 document object model and depends on VML rendering, attachEvent, and window.createPopup APIs that are either removed or rewritten in IE11 Edge mode.

3.3 Removal of legacy navigator properties and JScript behavior

The V6.1a bootstrap script reads window.navigator.userAgent and several legacy DOM properties to compute screen offsets and DPI. In IE11, several of these properties were deprecated, the screen DPI calculation path was changed, and the page silently throws a script error that aborts further picture load.

4. Pre-Installation Verification Checklist

Before declaring the V6.1a / IE11 combination dead, run through the following checks. The first three items are the steps the user already executed; the remaining items are the deeper checks that frequently surface additional gaps.

1. Confirm Compatibility View is active for the WebNavigator site. In IE11, open Tools > Compatibility View settings and add the WebNavigator server FQDN. The icon in the address bar should turn blue.
2. Verify the WebNavigator Client add-on is enabled. Tools > Manage add-ons > show All add-ons > locate WebNavigator Client Control (class id 3F2D5C7C-1B3F-4F0A-8B91-1A6E2C0E3B41 or the CLSID documented in your installation) and confirm status = Enabled.
3. Confirm Windows Firewall and any EDR/host firewall allow inbound TCP 80/443 to the WebNavigator server and outbound from the operator station on the temporary range the WebNavigator Control uses for picture streaming.
4. Confirm IE11 Enhanced Security Configuration (ESC) is disabled for the Administrators / Users zone on the operator station, otherwise ActiveX is blocked at the zone level even when the add-on is enabled.
5. Verify the WebNavigator Client setup log. Check %ProgramFiles%\Siemens\Automation\WebNavigator Client\Install.log for missing prerequisites (Visual C++ 2005/2008 redistributables, MSXML 6).
6. Enable script debugging just once. Tools > Internet Options > Advanced > Disable script debugging (Internet Explorer) unchecked. Reload the page and capture the exact line and error number from the yellow triangle. The most common one is SCRIPT438: Object doesn't support property or method 'createPopup'.
7. Check the F12 Developer Tools console for cross-origin / mixed-content blocks caused by HTTP-to-HTTPS site bindings.

5. Workaround A — Substitute WinCCViewerRT

WinCCViewerRT is a standalone runtime that displays WinCC pictures on a remote machine without requiring Internet Explorer. It is delivered on the WinCC installation medium in the WinCC\WinCCViewerRT folder and is licensed as part of the WebNavigator client access count.

5.1 Prerequisites

• WebNavigator license with at least one client access (the same license is consumed by WinCCViewerRT).
• WebNavigator server reachable on TCP 80/443 plus the configured picture download port (default 81/1443 for HTTPS).
• Windows 7 SP1 / Windows 10 / Windows Server 2008 R2 or later operator station.

5.2 Installation

1. Copy the WinCCViewerRT folder from the WinCC DVD to the operator station (or run the setup over the network share).
2. Run setup.exe as Administrator. Accept the license agreement.
3. Choose Install as a service if the operator station is a dedicated panel PC; choose Install as an application for engineering or test stations.
4. Reboot the operator station.

5.3 Configuration

1. Start WinCCViewerRT. The configuration dialog opens on first launch.
2. Enter the WebNavigator server name exactly as it appears in the WebNavigator certificate (FQDN, not IP address) and select HTTPS if the server is configured for it.
3. Enter the start picture (e.g. start.pdl).
4. Set the runtime language and time-zone handling to match the project.
5. Click Apply and confirm the test connection succeeds.

5.4 Operating modes

5.5 Verification

1. WinCCViewerRT must display the configured start picture within 10 seconds of launching on a LAN, 30 seconds on a WAN with <100 ms RTT.
2. Right-click inside the picture: the WinCC context menu must show operator input fields, language switch, and (if licensed) hardcopy export.
3. From the WebNavigator Server, open the WebNavigator Diagnostics page (http://<server>/WebNavigator/Status) and confirm the WinCCViewerRT client is listed with a green status indicator.

6. Workaround B — Upgrade the WebNavigator Project to V7.4 or Later

Siemens officially supports Internet Explorer 11 from WinCC/WebNavigator V7.4 onward. The V7.4 release ships a re-engineered WebNavigator Client ActiveX control with an updated compatibility manifest, IE11-aware document mode handling, and a rewritten bootstrap that uses the IE11-standard DOM exclusively.

6.1 Upgrade planning matrix

6.2 Migration steps

1. Inventory the project. Export all C / VB scripts, custom DLLs, user archive structures, and the redundancy configuration. Note any OPC tags that reference third-party servers.
2. Back up the runtime project. Copy the entire <ProjectName>.mcp directory and the RT directory to a versioned backup location.
3. Run the project migrator on the engineering station against a copy of the project. Resolve every Warning and Error row in the migration report before proceeding.
4. Open the migrated project in WinCC Explorer 7.4 SP1 and recompile all pictures (OS Project Editor > Rebuild all).
5. Install the WebNavigator V7.4 SP1 server on the same host (or a dedicated VM) using the SIMATIC WinCC V7.4 SP1 installation medium.
6. Install the WebNavigator V7.4 SP1 client on each operator station. The new client setup detects and removes the V6.x client first.
7. Repoint the operator stations to the new server. Bookmark the new https://<server>/WebNavigator/ URL.
8. Re-issue operator rights in the WinCC User Administrator; the user database is preserved but role assignments must be re-applied if you used the legacy SIMATIC Logon connector.

6.3 Verification after upgrade

• Launch the client on IE11 in Edge document mode (the default) and confirm the picture loads within 5 seconds.
• Switch the F12 emulator to IE10 standards and IE9 standards to verify backward compatibility for any IE10-era panels still in service.
• Verify that document.getElementById("WebNavigator") returns a valid object and that WebNavigator.ServerName reports the expected FQDN.
• Test every operator input element (button, I/O field, slider, trend) to confirm event round-trip.

7. Browser Compatibility Matrix

8. Alternative: Migrate to WinCC WebUX (V7.4 and later)

If the long-term objective is to leave Internet Explorer entirely, evaluate the WebUX option that ships with WinCC V7.4 and later. WebUX is an HTML5-based, browser-agnostic web server for WinCC pictures and is delivered as a separate runtime. It supports modern browsers (Edge Chromium, Chrome, Firefox, Safari) on Windows, iOS, and Android clients and is the strategic direction for greenfield WinCC web projects. Migration from a V6.x WebNavigator project to WebUX requires re-authoring the navigation concept but re-uses the same WinCC pictures and tags.

8.1 WebUX vs. WebNavigator — when to pick which

9. Diagnostic Decision Flowchart

10. Configuration Hygiene for the V6.1a Client (If You Must Stay)

Some plants operate under a long change-control window and cannot migrate immediately. If you must keep the V6.1a client running for a defined period, the following configuration stack maximises the chance of the client starting on IE11 even though it is unsupported.

1. Pin the WebNavigator server URL to the IE11 Compatibility View list (Tools > Compatibility View settings > Add).
2. Set the registry value HKCU\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION » iexplore.exe = 8888 (decimal, IE8 standards) to force the document mode.
3. Disable IE11 Enhanced Security Configuration in Server Manager > Local Server > IE Enhanced Security Configuration.
4. Add the WebNavigator server to the Trusted Sites zone and lower the zone security to Medium-low.
5. Install the Visual C++ 2005 SP1 and 2008 SP1 redistributables on the operator station (prerequisites for the V6.x COM control).
6. Disable the Windows SmartScreen filter for the WebNavigator URL via Group Policy if it is blocking the ActiveX download.
7. Set the WebNavigator Client add-on to Run without permission in the Manage add-ons dialog.

11. Acceptance Test Checklist

Whichever workaround you adopt, the following acceptance test confirms a stable deployment:

• Operator station boots cold, logs in, and the picture is interactive within 30 seconds.
• Hardcopy export produces a valid .emf / .pdf / .prn output (depending on configured printer).
• User change works (operator logs out, new operator logs in, picture reloads).
• Language switch works (if the project is multi-lingual).
• Alarm line and alarm window both update within 2 seconds of a tag change at the PLC.
• Trend and table controls replay historical data from the WinCC Tag Logging archive.
• Server failover (if redundancy is configured) completes in < 30 seconds with no client-side error.
• WebNavigator diagnostics page reports a green client status for every connected station.

12. Frequently Asked Questions