Qt Ошибка линковщика LKN2019

Question

нужно помочь с qt 5.12, а точнее с линковщиком. Постоянно видает ошибку, хоть что не делай(Хотя оно работало) разрядность какая нужно стоит, qmake не помогает:

*.pro

QT       += core gui
QT += widgets
QT += core

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Projects
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain             
version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs         
deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QApplication>
#include <QMessageBox>
#include <QFile>
#include <QFileDialog>
#include <QTextStream>
#include <QString>
#include <QPushButton>
#include <QTextEdit>

using namespace std;


QString SaveToFile(const QString Path, const QString Text){

    QFile file(Path);

    if(!file.open(QFile::WriteOnly | QFile::Text)){
        return "Path not Correct!";
    }else if (Path == "File Path") {
        return "Not choose file!";
    }

    QTextStream stream(&file);

    stream << Text;

    file.close();

    return "Successful saved";
}


QString ReadFile(const QString Path){
    QFile file(Path);

    if(!file.open(QFile::ReadOnly | QFile::Text)){
        return "Path not Correct";
    }

    QTextStream stream(&file);
    QString res = stream.readAll();

    file.close();
    return res;
}


MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->PathLabel->setReadOnly(true);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_actionOpen_triggered()
{
    QString filePath = QFileDialog::getOpenFileName(this, tr("Open file"),"D://");
    ui->PathLabel->setText(filePath);

    QString text = ReadFile(filePath);

    ui->textEdit->setText(text);
}

void MainWindow::on_actionSave_triggered()
{
    QString res = SaveToFile( ui->PathLabel->toPlainText(), ui->textEdit->toPlainText());
    QMessageBox::information(this, "Information",res);
}


void MainWindow::on_actionCreate_triggered()
{
    QString Path = QFileDialog::getSaveFileName(this, tr("Save File"),"D://", tr("*"));
    QString res = SaveToFile( Path, ui->textEdit->toPlainText());
    ui->PathLabel->setText(Path);
    QMessageBox::information(this, "Information",res);
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

public slots:
    void on_actionOpen_triggered();

    void on_actionSave_triggered();

    void on_actionSave_as_triggered();

    void on_actionCreate_triggered();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

Answer 1

Сталкивался с подобной проблемой, мне помогли следующие действия:

1. Меню -> сборка -> очистить всё
2. запустить qmake
3. После этих действий пересобрать проект