telegram bot breaks down when it is used by more than one person

After more than one person uses the bot, the error 2022-06-03 19:46:12,641 (init.py:648 MainThread) ERROR - TeleBot appears: "A request to the Telegram API was unsuccessful. Error code: 400. Description: Bad Request: message text is empty". I read a lot of things, but nothing helped

import telebot
from telebot import types
import gspread
from registration_sheet import gs, sh
from button import button1, button2, mm


token = 'token'
txt = open("C:/Users/nmash/Desktop/Cloud/terms_of_the_agreement.txt", encoding = "utf-8")

class Telegrambot():

    def __init__(self, token):
        super(Telegrambot, self).__init__()
        self.bot = telebot.TeleBot(token)
        self.message_handler()
    
        self.start()

    def start(self):
        self.bot.polling(none_stop=True)
    
    def message_handler(self):
        @self.bot.message_handler(content_types=['text'])

        def message_worker(message):            
        
            if message.text == '/start':
                button1()
                self.bot.send_message(message.from_user.id, txt.read(), reply_markup=mm)            
                            
                #self.bot.send_message(message.from_user.id, "Вы приняли условия соглашения✅", reply_markup=mm)
            if message.text == "Принять условия соглашения✅":
                self.bot.send_message(message.from_user.id, "Вы приняли условия соглашения✅", reply_markup=types.ReplyKeyboardRemove())
            
                self.registration(message)

    def registration(self, message):        
        def message_han(message):
            sent = self.bot.send_message(message.from_user.id, 'Введите своё имя:')
            self.bot.register_next_step_handler(sent, reg)

        def reg(message):           
            name = message.text             
    
            worksheet = sh.sheet1 
            values_list = worksheet.row_values(2)

            number = 0
            while True:
                n = number + 1
                number = n
                values_list = worksheet.row_values(number)
                if values_list == []:
                    userId = number
                    break

            worksheet.append_row([name, userId])

            self.bot.send_message(message.from_user.id,  "Ваше имя: " + name + "\nВаше ID: " + str(number))

        message_han(message)    

Telegrambot(token=token)