It's possible to use a dll file built on DotNet Framework 4.5 into a DotNet Framework 1.1 as project reference?

Question

I have a dll file built on .Net Framework 4.5 and I need for a particular reason, use this dll to be reference in a .Net Framework 1.1. Please don't ask me why I am using a 1.1 project :) When I try to import the dll's reference I get a message telling me it's not a valid assembly or COM component. Thanks!

Answer 1

No. It is not possible. You can't use a dll developed in .Net framework 4.5 in an older version of the framework.

See: Version Compatibility in the .NET Framework

Answer 2

Short answer no. Because each framework introduces new features and changes some of the existing ones.

The only way is to migrate your .net 1.1 project into .net 4.5 (although .net supports forward compatibility ).

Answer 3

Actualy you can do this by wrapping the .net4.5 dll in com , and accessing it in .net1.1 using com dll import. I haven't got the time to write a sample but take a look at this article, its a bit messy to do this but it should work even in .net 1.1 , the article mentions .net2.0 but its the same principle for .net1.1

How to use .Net4 based dll in earlier framework