Support for SHA-2 has improved over the last few years. Most browsers, platforms, mail clients, and mobile devices already support SHA-2. However, some older operating systems such as Windows XP pre-SP3 do not support SHA-2 encryption.

We encourage users running older, less secure systems to upgrade.

This page lists the minimum version required for SHA-2.

Browser SHA-2 Support

Browser Minimum Browser Version
Chrome 26+
Firefox 1.5+
Internet Explorer 6+ (With XP SP3+)
Konqueror 3.5.6+
Mozilla 1.4+
Netscape 7.1+
Opera 9.0+
Safari 3+ (Ships with OS X 10.5)

Operating System SHA-2 Support

Operating System SSL Certificate Minimum OS Version
Android 2.3+
Apple iOS 3.0+
Blackberry 5.0+
ChromeOS yes
Mac OS X 10.5+
Windows XP SP3+
Windows Phone 7+

Above information is excerpted from