Is there a workaround to IE7's user agent being defaulted after installing .Net Framework 3.5 SP1?

Question

I have verified that after installing the .Net Framework 3.5 SP1, when the User Agent string exceeds a certain number of characters, the user agent is defaulted to 'userAgent string:Mozilla/4.0 (compatible; MSIE 6.0)'. I've verified this behavior on several machines but can't seem to find a suitable workaround. This is preventing some Silverlight applications from running when the user's browser (IE7) is falsely reporting the user agent. Prior to installing 3.5 SP1, the user agent was correct in reporting browser version and .Net framework versions.

Answer 1

You're probably referring to the known bug in .Net 3.5 SP1 where the user agent is incorrectly being reported when the length is exceeded. According to the MS bug report and other tidbits I dug up when looking into this, there are the following workarounds. Some may or may not be suitable for your situation.

• Remove some versions of the .Net framework on the machine(s) in question. Only keep around major versions to reduce the user agent reporting.
• Edit the registry at the following location: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform
• Using above reg key, remove duplicate entries
• Using above reg key, remove entries that are no longer needed or irrelevant.

This doesnt help public facing websites, however. I'm hoping MS fixes this bug in the very near future, as it's preventing availability of certain SL sites to users who don't know what's going on or how to resolve it.