For Analyzer version 3.0.2361
If you are getting the error "A potentially dangerous Request.Form value was detected from the client" after upgrading to 3.0.2361
Please check your Analyzer's Web.config file, search for "httpRuntime", verify to see if requestValidationMode="2.0" is defined.
<httpRuntime maxRequestLength="50000" requestValidationMode="2.0" executionTimeout="2000" />
This was introduced in version 3.0.2361 which now uses .NET 4.x, so if you have copied the old Web.config then it is likely missing.
As a general rule, always do a comparison between the newly installed Web.config file since it often changes according to changes we made.