The type or namespace name 'AddressableAssets' does not exist in the namespace 'UnityEngine'

I tried to use addressables to optimize memory usage in my WebXR project and added Addressables Package via Package Manager. However when i try to use it in code editor editor console shows this errors:

error CS0234: The type or namespace name ‘AddressableAssets’ does not exist in the namespace ‘UnityEngine’ (are you missing an assembly reference?)

error CS0234: The type or namespace name ‘ResourceManagement’ does not exist in the namespace ‘UnityEngine’ (are you missing an assembly reference?)

I was looking for a solution on the internet, I tried to delete all the .csproj files in project folder and then rebuilding them but without any success.

Is there a way to fix this problem?

Unity version: 2020.3.16f
Universal Renderer Pipeline

I am getting the same missing namespace errors even though the addressable package is correctly installed. I can configure my groups and build bundles, so I’m just scratching head.

Have you found a solution to this issue?