Unity Scripts edited in Visual studio don't provide autocomplete

Question

When I want to edit C# Unity scripts, they open in Visual Studio. It is supposed to provide auto complete for all Unity related code, but it doesn\'t work.

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Answer 1

Try with combination: Ctrl + Alt + Space

Answer 2

In my case, correct .net version was not installed on my PC. I install the .net 3.5 on my pc and that worked for me.