Can't include mainwindow.h

Question

Getting errors when including mainwindow.h (in my project it's called viewwindow.h) in other header file (in controller.h). Controller.h is located in folder Controller.

Errors that i got in viewwindow.h:

1. C2143: syntax error: missing ';' before '*'
2. C4430: missing type specifier - int assumed. Note: C++ does not support default-int
3. C2238: unexpected token(s) preceding ';'

And they all are pointing to line ControllerClass *pController;

If it's a stupid question then help me and smash that dislike button. I deserved it.

viewwindow.h

#pragma once
#include <QMainWindow>
#include "Controller/controllerclass.h"

namespace Ui {
class ViewWindow;
}

class ViewWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit ViewWindow(QWidget *parent = nullptr);
    ~ViewWindow();

private slots:
    void on_ExitAction_triggered();

private:

    // Main UI
    Ui::ViewWindow  *ui;

    // Controller sends user input to EditorFacade class
    ControllerClass *pController;
};

viewwindow.cpp

#include "viewwindow.h"
#include "ui_viewwindow.h"

ViewWindow::ViewWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::ViewWindow)
{
    ui->setupUi(this);

    pController = new ControllerClass();
}

ViewWindow::~ViewWindow()
{
    delete pController;
    delete ui;
}

void ViewWindow::on_ExitAction_triggered()
{
    QApplication::quit();
}

controllerclass.h

#pragma once
#include "viewwindow.h"

class ControllerClass;
class ControllerClass
{
public:

    ControllerClass();

};

controller.cpp

#include "controllerclass.h"

ControllerClass::ControllerClass()
{

}