FLASK：请求的 URL 不允许使用该方法

Question

我不断收到“请求的 URL 不允许使用该方法”
对不起，如果代码看起来写得不好，但我仍然是初学者，是的。
希望你能找出我犯的错误并帮我改正！
提前致谢

Python 代码：

@app.route("/register/student", methods=["POST"])
def student_register_post():
    # handle post data
    email = request.form['email']
    password = request.form['password']
    course = request.form['course']
    #check if there is input in both fields
    if(email!="" and password!=""):
    # check if user exists
        if database.get_user_by_email(email) is not None:
            # print(database.get_user_by_email(email))
            return "An account with this email already exists."

        # create and add user
        tuser = User(email, password, course)
        database.add_user(tuser)

        # automatically login user
        login_user(tuser)

        return redirect('/protected_place')
    else:
        return redirect('/register/student')

HTML 表单：

    <form id="form" action="/register" method="post">
        <div id=inputs>
            <label id="courses_label" for="course"><b>Course</b></label>
            <select name="course" id="course" form="form" required>
                <option value="11A">11A</option>
                <option value="11A">11B</option>
                <option value="11A">11C</option>
                <option value="11A">11D</option>
            </select>
            <label><b>E-mail</b></label>
            <input name="email" type="text" placeholder="Ex: mail@notgmail.com"/>
            

            <label><b>Password</b></label>
            <input name="password" type="password" placeholder="Ex: 123456 (please don't use that)"/>

        </div>
        <input id=register_button type="submit" name="register_button" value="Register">
    </form>```