我不明白為什么我會收到此錯誤：raise exception_class(message, screen, stacktrace) selenium.common.exceptions.StaleElementReferenceException: Message: The element reference of <a id="u153-popover-trigger--3926" class="udlite-custom-focus-visible browse-course-card--link--3KIkQ" href="/course/kafka-streams-real-time-stream-processing-master-class/"> is stale; either the element is no longer attached to the DOM, it is not in the current frame context, or the document has been refreshed我使用 WebDriverWait 兩次來檢查是否加載了新頁面：如果新頁面的分頁鏈接發生相應變化如果新頁面的課程列表div元素被加載  from selenium import webdriver    from selenium.webdriver.common.keys import Keys    from selenium.webdriver.firefox.options import Options    from selenium.webdriver.common.by import By    from selenium.webdriver.support.ui import WebDriverWait    from selenium.webdriver.support import expected_conditions as EC    from selenium.common.exceptions import TimeoutException        def waitForLoad(inputXPath):         Wait = WebDriverWait(driver, 10)        Wait.until(EC.presence_of_element_located((By.XPATH, inputXPath)))        options = Options()    options.headless = True    driver = webdriver.Firefox(options=options, service_log_path='NUL')        driver.get("https://www.udemy.com/courses/development/?sort=highest-rated")        courses = []    f = open("0udemy.txt","a", encoding="utf-8")    page = 1        try:        waitForLoad("//div[@class='filter-panel--paginated-course-list--2F0x1']")    except TimeoutException as e:        print("timeout!")        while True:        ## I also tried that :         #courses = driver.find_elements_by_xpath("//div[@class='course-list--container--3zXPS']//a[contains(@class, 'browse-course-card--link--3KIkQ')]")        #for i in courses:        #    f.write(f"{i.get_attribute('href')}\n")我在第 20 頁和第 80 頁之間收到陳舊錯誤。我的世界紀錄是第 78 頁。