"Sites" button and "Custom Level" slider are grayed out in Internet Options - Security tab

When you open Internet Options - Security tab and click on any Zone (except Internet Zone), the Sites button may be grayed out. As a result, you may be unable to add or remove a website to the specified Zone. Additionally, you may also notice that the Custom level slider is grayed out. This prevents you from customizing the Security level for that particular Zone.

The Flags value in the registry governs the above two options (and more) for each Zone.

To enable the Sites button and the Custom Level slider for that particular Zone, follow these steps:

Open Registry Editor (regedit.exe) and navigate to:

HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\{Zone ID}


{Zone ID}

Local intranet


Trusted sites




Restricted sites


In the right-pane, double-click Flags and click Decimal

Add 3 to the existing Value data

Example: If Flags value reads 0 (Decimal), set it to 3 (i.e., 0 + 1 + 2)

Flags value



Allow changes to custom settings
2 Allow users to add Web sites to this zone
4 Require verified Web sites (https protocol)
8 Include Web sites that bypass the proxy server
16 Include Web sites not listed in other zones
32 Do not show security zone in Internet Properties
64 Show the Requires Server Verification dialog box

Treat Universal Naming Connections (UNCs) as intranet connections

Close Registry Editor and open a new instance of Internet Explorer

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