文件输入错误

试试这样：

import csv
import datetime
import os
from random import randint
import openpyxl
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMessageBox


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(1223, 578)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")

        self.verticalLayout = QtWidgets.QVBoxLayout(self.centralwidget)
        self.verticalLayout.setObjectName("verticalLayout")
        self.QuestionField = QtWidgets.QTextBrowser(self.centralwidget)
        self.QuestionField.setObjectName("QuestionField")
        self.verticalLayout.addWidget(self.QuestionField)
        self.EntryField = QtWidgets.QPlainTextEdit(self.centralwidget)
        self.EntryField.setObjectName("EntryField")
        self.verticalLayout.addWidget(self.EntryField)
        self.ButtonNext = QtWidgets.QPushButton(self.centralwidget)
        self.ButtonNext.setObjectName("ButtonNext")
        self.verticalLayout.addWidget(self.ButtonNext)

        MainWindow.setCentralWidget(self.centralwidget)
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "Опросник"))
        self.ButtonNext.setText(_translate("MainWindow", "Далее"))


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        super().__init__()
        self.setupUi(self)

        self.question_list = [] 
        
        self.question = ''                                             # +++ 
        self.ammount_of_questions = 4                                  # +++  
        
        self.wb_obj = openpyxl.load_workbook("questions.xlsx")  
        self.ButtonNext.clicked.connect(self.get_next_question)  

        self.start_quiz()
        self.get_next_question()

    def get_next_question(self):
# +++
        num_question = len(self.question_list)                         # +++ 
        print(f'num_question ==={num_question}===')                    # 
        
        if num_question < 3:
            wb_sheet = self.wb_obj['Block_1']
        elif num_question == 3:
            wb_sheet = self.wb_obj['Block_2']
        elif num_question == 4:
            wb_sheet = self.wb_obj['Block_3']
        else:
            # self.close()
            self.end_test()
            return
            
        answer = self.EntryField.toPlainText()
        rows = wb_sheet.max_row
        nums_wb = randint(2, rows)
        question = wb_sheet[f'A{nums_wb}'].value
        self.question_list.append(question)
        self.QuestionField.setText(question)
        
# +++
        if num_question:                                               # +++
#            self.write_to_file(question, answer)
# ---------------------------> vvvvvvvvvvvvv <------------------------------
            self.write_to_file(self.question, answer)                  # +++
            print(num_question, '--', self.question, '--', answer)
            self.EntryField.clear()
# +++            
        self.question = question                                       # +++
        
        if num_question == self.ammount_of_questions:                  # +++
            self.end_test()                                            # +++
            return                                                     # +++

# +++ vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    def end_test(self):
        self.QuestionField.clear()
        self.ButtonNext.setEnabled(False)
        self.EntryField.setEnabled(False)
        msg = QtWidgets.QMessageBox.information(
            self, 
            'Тест закончен', 
            'Cпасибо за участие, хорошего вам дня.'
        )
            
        self.QuestionField.setText('''
        Тест закончен, спасибо за участие.
        Ваши результаты:
        тут можно что-то написать о результатах тестирования.
        ''')
# +++ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    

    def write_to_file(self, question, answer):
        with open(f"{os.getlogin()}_{datetime.date.today()}.csv", 'a',
                  encoding='cp1251', errors='replace', newline='') as file:
            writer = csv.writer(file, delimiter=';')
            writer.writerow([question, answer])

    def start_quiz(self):
        greetings = QMessageBox()
        greetings.setWindowTitle('Приветствие')
        greetings.setText(
            f'Приветствую Вас {os.getlogin()}. Предлогаю в начале рабочего дня пройти тебе тест на знание наших цен и предложений')
        greetings.setIcon(QMessageBox.Information)
        greetings.exec_()


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.resize(300, 400)
    w.show()
    sys.exit(app.exec_())