[Solved] async not working with Visual Studio 2010 and .NET 4.0? [duplicate] August 22, 2022 by Kirat async and await have been introduced in C# 5. Visual Studio 2010 supports C# 4. Thats why you can’t compile code with async/await under VS 2010. 3 solved async not working with Visual Studio 2010 and .NET 4.0? [duplicate]