NULL reference exception while reading user sessions (Reflection)

Question

I have implemented the code for reading the active sessions using the reference Reading All Users Session and Get a list of all active sessions in ASP.NET.

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Answer 1

It sounds like a different version (or update) of .NET is running on 2003 than you have on XP / Win7, although it could also just be a platform-specific difference. If it was permissions / trust, you would have seen an exception. Instead, it seems more likely that simply: _caches does not exist on whatever version is on the 2003 machine. If you use reflection to access private state: you should entirely expect it to explode between versions / updates / platforms / at-whim / etc.

To investigate:

• check whether obj is null
• check whether obj.GetType().GetField("_caches", BindingFlags.NonPublic | BindingFlags.Instance) is null

(either of those things could cause this exception on the line you cite)