Google Maps is handled via JavaScript. This isn't dependent on the version of the .NET runtime, so you shouldn't need to change the mapping side. What you may need to change is your ASP.NET code if you are using .NET 3 or .NET 4 features, and there's nobody here who could help you with that without seeing your source code. Change the project type to .NET 2 in your solution and recompile the application. See what defects this causes and fix as necessary. In future, you might want to check such basic things as the target framework before commencing any work.
Forgive your enemies - it messes with their heads
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