AsyncGPUReadbackRequest could not found

I am getting errors like
“The type or namespace name ‘AsyncGPUReadbackRequest’ could not be found (are you missing a using directive or an assembly reference?)”

“The name ‘AsyncGPUReadback’ does not exist in the current context”

Although I have included using UnityEngine.Experimental.Rendering. Can you please tell me how to resolve this issue?

I am using Unity 5.6.4p4.

Unity 5.6.4p4 is quite old and UnityEngine.Experimental.Rendering as far I know was added in the newer versions from 2017.1 and beyond. You can try download the off line doc’s (could not find it online in my 5 secs research) and see if it’s there, maybe under a different namespace.

Thanks for your help @lassade.

Actually I tried to install the unity 2018.1.0.b1(latest beta version). It was working there properly but problem is when I am opening my project there its showing several compilation error (just like obsolete namespaceand others). Its really very difficult to check all namespaces for a huge project and change those. Is there any other way to resolve these kinds of issues?

After opening my project to unity 2018.1.0.b1, I am trying to open it in unity 5.6.4p4 but its crashing. I don’t know why? Can you please tell me.