Website Forcing IE5 Compatibility Mode Despite Enterprise Configuration: A Troubleshooting Journey

I had an issue reported to me where a portal configured to use IE10 compatibility mode through Enterprise Mode Site List was consistently loading in IE5 mode instead. Despite correctly configuring the Enterprise Mode XML, the site would drop to IE5 compatibility mode when accessed through the Intranet zone with automatic Windows authentication enabled.

Initial Setup and Configuration

Creating the Enterprise Mode Site List

First, I used the Enterprise Mode Site List Manager tool to create the configuration. This tool is essential for generating properly formatted XML and maintaining version control. You can download it from Microsoft:

• Enterprise Mode Site List Manager (schema v.2)

Then from there you can add the website and choose the options you require as below:

 

The options will look like this, here we can see we need to use IE11 in compatibility mode 10:

The initial XML configuration looked like this:

<site-list version="10">
  <created-by>
    <tool>EMIESiteListManager</tool>
    <version>12.0.0.0</version>
    <date-created>12/09/2025 14:05:45</date-created>
  </created-by>
  <site url="oldserver.bear.local">
    <compat-mode>IE10</compat-mode>
    <open-in>IE11</open-in>
  </site>
</site-list>

Deploying via Local Group Policy

I deployed this configuration using Local Group Policy and hosting it on a web server:

1. Open Group Policy Editor (gpedit.msc)
2. Navigate to: Computer Configuration > Administrative Templates > Windows Components > Internet Explorer
3. Enable "Use the Enterprise Mode IE website list"

Set the path to the remote XML file (served for me with IIS)

Checking Current Compatibility Mode

To verify what mode the site was actually using:

1. Navigate to the site in Edge
2. Look for the IE mode indicator (blue IE icon) in the address bar
3. Open Developer Tools (F12) and check the Emulation tab

The site consistently showed "Compatibility Mode: IE5" instead of the configured IE10

Verifying Enterprise Mode Configuration

I used these Edge commands to verify the configuration:

edge://compat                    # Main compatibility page
edge://compat/enterprise         # View Enterprise Mode Site List
edge://compat/iediagnostic      # Detailed IE mode diagnostics

After any XML changes:

1. Navigate to edge://compat
2. Click "Force update"

Verify the site appears with correct settings in edge://compat/enterprise

Checking Group Policy Application

To ensure policies were applied correctly:

gpupdate /force
gpresult /h gpresult.html

Then reviewed the HTML report for any conflicting policies related to:

• Compatibility View settings
• Intranet zone configurations
• Enterprise Mode settings

The Zone-Specific Behavior

The critical finding was that the site behaved differently based on security zones:

1. In Intranet Zone: Automatically dropped to IE5 mode
2. In Internet Zone: Correctly displayed in IE11 mode (when canceling authentication)
   
   
   

This pointed to Intranet zone-specific settings overriding the Enterprise Mode configuration.

Understanding the Root Cause

According to Microsoft's documentation, by default IE11 uses the "Display intranet sites in Compatibility View" setting. When this is enabled, it forces sites to use IE7 compatibility mode, which then drops to IE5 Quirks mode if the page doesn't have a proper DOCTYPE declaration.

Attempted Solutions

1. Enhanced XML Configuration with docMode

I tried adding explicit document mode settings:

<site url="oldserver.bear.local">
    <compat-mode>IE10</compat-mode>
    <open-in>IE11</open-in>
    <docMode>10</docMode>
</site>

2. Group Policy Modifications

I enabled "Turn on Internet Explorer Standards Mode for local intranet":

• Location: Computer Configuration\Administrative Templates\Windows Components\Internet Explorer\Compatibility View
• This should prevent intranet sites from automatically using compatibility view

3. Disable Automatic Intranet Detection

Disabled automatic intranet network detection to prevent override behaviors:

1. Internet Options → Security → Local Intranet → Sites
2. Unchecked "Automatically detect intranet network"

4. Quirks Mode Policy

Configured "Use Policy List of Quirks Mode sites" with a dummy entry to prevent automatic quirks mode:

• Added example.invalid as a placeholder
• This policy requires at least one site to save

5. Disable Compatibility at Registry Level

Applied registry modifications to force disable compatibility behaviors:

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\BrowserEmulation]
"IntranetCompatibilityMode"=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION]
"iexplore.exe"=dword:00002710
"msedge.exe"=dword:00002710

The Real Problem: SAP Portal Server-Side Configuration

The “portal” was a SAP portal and despite all these configurations, the site continued to load in IE5 mode when:

1. Located in the Intranet zone
2. Using automatic Windows authentication
3. Successfully authenticating with domain credentials

The behavior suggested that the SAP Portal itself was detecting the authentication method and zone, then forcing IE5 Quirks mode through server-side logic.

SAP Portal Specific Issue

Research revealed that SAP Portal has its own way of handling browser compatibility. According to a SAP Q&A discussion on Document Mode and Enterprise Mode, "EP has it's own way of handling quirks mode (IE5 mode/old IE7 mode) that is the browser document mode iView."

Verification

When the authentication prompt was canceled (preventing automatic login), the site correctly displayed in IE11 mode. This confirmed that the compatibility mode change occurred after successful Windows authentication, pointing to server-side behavior rather than client configuration.

Resolution

The issue appears to be originating from the SAP Portal server configuration rather than the client-side Enterprise Mode settings. The portal is likely:

1. Detecting the Intranet zone and Windows authentication
2. Sending specific headers or implementing logic that forces IE5 Quirks mode
3. Overriding any client-side Enterprise Mode configurations

Conclusion

1. Always use the Enterprise Mode Site List Manager tool for consistent XML generation
2. Test sites in different security zones to identify zone-specific behaviors
3. Use Edge diagnostic tools (edge://compat) to verify configurations
4. When client-side configurations don't work, investigate server-side behaviors
5. SAP Portal has its own compatibility mode handling that can override Enterprise Mode settings

The combination of Intranet zone detection and Windows authentication triggering server-side compatibility logic makes this a complex issue that requires both client and server-side investigation to fully resolve.