咨询：IE 11用户代理字符串中SLCC2的含义

Great question—this is one of those obscure UA string tokens that’s easy to overlook, especially since official documentation is pretty sparse! Let me break this down for you:

What is SLCC2? #

SLCC2 stands for Microsoft Shared Live Communications Client 2. It’s a shared component from older Microsoft Office suites (primarily Office 2010 and 2013) tied to early enterprise real-time communication tools like Microsoft Lync (the direct predecessor to Microsoft Teams). When this component is installed on a user’s system, it automatically adds the SLCC2 tag to Internet Explorer’s user agent string.

Why Might It Be Causing Site Issues? #

Since this component deeply integrates with IE, it can alter the browser’s default behavior in subtle, site-breaking ways:

• It injects a browser extension/plugin that may interfere with JavaScript execution, DOM rendering, or resource loading workflows
• It might force IE into a specific compatibility document mode that your site isn’t optimized for
• It can tweak security settings or cookie handling logic that your site relies on to function properly

Troubleshooting Tips #

If you’re only seeing issues with users who have SLCC2 in their UA, try these actionable steps:

• Test your site in an IE environment with the Office 2010/2013 SLCC2 component installed to replicate the exact issue
• Audit your IE-specific compatibility code to see if it needs adjustments to account for this component’s presence
• Guide affected users to disable the SLCC2-related IE plugin (via IE’s "Manage Add-ons" menu) as a temporary workaround
• Consider pushing a targeted message to these users recommending a modern browser (like Edge) for better, more reliable compatibility

内容的提问来源于stack exchange，提问作者Tim Bobo