ASP.NET mysterious compile error

When I compile .NET solution, which is an ASP.NET 3.5 website project and a few class libraries, sometimes we get COMPILE error "Object reference not set to an instance of an object". Doesn't give you any additional information, like it usually does - which project, file, li开发者_如何转开发ne of code or anything like that. Usually if you stop and re-compile it disappears but re-appears once in a while. Some developers think it comes from report control that we use to view SSRS reports but no one is certain. Same happens with everyone on a project. How would you investigate this kind of problem, what would you look at first, and what kinds of tools would you use.

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It could be that your designer files are out of sync with the aspx. There maybe references to controls that no longer exist in the web form.

I'd also suggest taking a look at the Output window (View > Output). That might give you more clues as to where the error is happening.