.NET Framework deprecated interfaces and attributes. What was your biggest refactoring due to lack of support?

Some .net-framework interfaces and attributes become obsolete and deprecated since new framework version appears. I am warned that such code may be removed or become unpredictable in next versions but have you ever faced the situation when you were forced to refactor code because code came uncompilable or start to behave weird? What was you biggest refactoring开发者_StackOverflow中文版?

Or maybe Microsoft always continued to support api's once they were published?

Thank you in advance!

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Practically no refactoring at all. When converting from .NET 1.1 to 2.0, there was a lot of stuff that was automatically generated for compatibility, which I took out again because it wasn't necessary. Some code could be improved when generics was introduced, but there have been almost no issues with existing code breaking for me.