25Mar/080
Do security updates! (and remember to include that in the requirements of the server specification)
In one of the projects I was technical architect in we were struggling with strange error. When accessing main URL of the application we were getting NullReferenceException. But when accessing same site with language code at the end of URL everything was ok. What was the problem? Lack of SP1 for .Net Framework 2.0 installed.
There is also second lesson. Be very detail when crating specifications. When we were delivering server specification we told the Administrator that we will need .Net Framework 2.0. We forgot to mention that all security updates has to be installed on the server.
Here is the link to the problem and it's solution description.