Many many errors when compiling in Unity 2018.3.7?

Question

Android

When compiling the project, I get about 166 identical errors like

C:/Users/destrix/Desktop/SuperMegaCaseSimulator/Library/PackageCache/[email protected]/Scripts/Runtime/TextContainer.cs(2,19): error CS0234: The type or namespace name `EventSystems' does not exist in the namespace `UnityEngine'. Are you missing an assembly reference?

. As I understand it, this is due to the fact that the EventSystem cannot be found in the UnityEngine, although everything is displayed in the code. Am I thinking right? And how to solve it?

Answer 1

There in the left column with EventSystem all the rules?