`Shader' does not contain a definition for `Find'

i have imported Post processing stack and unity suddenly giving shader.find and shader.propertytoid defination not found error.

Im using unity 3d 2018.2

You most likely have created a class / script and named it “Shader”. Unity’s Shader class is located in the UnityEngine namespace. Since you most likely placed your class in the global namespace it will take precedence. Do avoid naming your own classes like a build in class. Or if you really have to, make sure you put it in your own seperate namespace to avoid naming conflicts.

Maybe Unity didnt uncompress the package well and you lost those shaders, it happened to me in 2018.3 with the HDRP