The .Net Framework has a feature called Shadow Copy. Shadow copy is enabled on every appdomain created by ASP.NET by default. By default assemblies loaded will be copied to a shadow copy cache directory, and will be used from that location. Why does ASP.Net do this? So the original file is not locked and can be modified. An interesting error I have ran into intermittently when running ASP.Net apps with the debugger is ‘Cannot create/shadow copy when that file already exists‘ I’m still not sure why this happens only on occasion, as I can often clean my solution, then reload a web app and it will work fine then. But if you are getting it frequently enough for it to affect your work, you can add the following to your app’s web.config or the master .Net web.config:
<system.web> <hostingEnvironment shadowCopyBinAssemblies="false" /> </system.web> Thanks Rana Faisal Munir
Dr. Rana Faisal Munir's Blog 
thanks, I did what you say, and this functioned satisfactorily
thnx dear.
thanx… it helped me a lot
thanx allllllllot….
Jeeta rahe rana…..
Thanks! This error was driving me nuts.
u saved my A$$ Buddy 😀
Cheers.
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