Tracking down intermittent 'Object reference not set to an instance of an object.' error on build

Question

I could use some help trying to track down an intermittent error that I\'ve been having with our ASP.Net project for quite some time.

Intermittently when building th

Answer 1

Check the Application Log of your Event Viewer - It should tell you where the exception is being thrown.

Answer 2

I've seen this when you have a web control in a page where there is invalid HTML. If your codebehind is trying to do something with the control, it won't be able to find it and will give you Object Reference... error at compile time. In my experience, it doesn't create a runtime error, and the project will build if the file in question is closed at the time of build. HTH, Good Luck!

Answer 3

• See if there are any post-build events that could be failing. These can be found on each project's property page.

• Try using Rebuild Solution instead of Build Solution. You may need to add Rebuild Solution from Tools > Customize. If your web app installs or registers any windows services, and those services are started, Rebuilding plows through those types of problems.

Answer 4

An "Object reference not set to an instance of an object" is clearly a run-time error, not a compile-time error. So what that says to me is that Visual Studio is choking on something, which may not necessarily be in your code, or which something in your code is only indirectly causing.

Next question I'd ask: Does this happen only in Visual Studio, or does the same thing show up when you build using MSBuild or CSC?

Answer 5

To follow up on this problem, we never did track down the origin of the error but it disappeared when we upgraded to Visual Studio 2008 and converted the project to a Web Application.

Answer 6

The first thing I'd try would be to increase the compiler verbosity. This can be set in the Visual Studio options - e.g. "Tools->Options->Projects and Solutions-Build and Run->MSBuild project build output verbosity" for VS2005. If you set it to diagnostic then it should tell you what it's doing at the time the exception is raised at the very least.