What is DLL HELL in .NET

Let us try and understand DLL HELL problem with an example. Please refer to the image below. 

1. I have 2 applications, A1 and A2 installed on my computer. 

2. Both of these applications use shared assembly shared.dll

3. Now, I have a latest version of Application - A2 available on the internet.

4. I download the latest version of A2 and install it on my machine.

5. This new installation has over written Shared.dll, which is also used by Application - A1.

6. Application - A2 works fine, but A1 fails to work, because the newly installed Shared.dll is not backward compatible.

So, DLL HELL is a problem where one application will install a new version of the shared component that is not backward compatible with the version already on the machine, causing all the other existing applications that rely on the shared component to break. With .NET versioning we donot have DLL HELL problem any more.


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