I was working on the Project Argon Assault and you are told to import the Standard Unity Assets. In unity 2019 the Assets package is no longer within the editor and must be installed from the unity asset store. But once you import the asset you are greeted with multiple errors and you will be unable to proceed in the tutorial.
I found a solution within the comments of the unity Asset store from a user named sam12sam12, the user has you modify the code of two files and then everything works. There are other threads about this problem in the forum however they no longer solve the issue.
You will need to edit the script named ForcedReset.cs and add in:
Using UnityEngine.UI;
At the the top and modify the line that starts out as [RequireComponent(typeof to the following:
[RequireComponent(typeof (Image))]
Then open the script named: SimpleActivatorMenu.cs and add the following to the top:
Using UnityEngine.UI;
Then modify the line that declares the camSwitchButton to the followin:
public Text camSwitchButton;
This worked for me, and I hope you find this helpful.