BadRequestKeyError

html file:

{% block content %}
{{ super() }}
<p><label>Найти человека</label><input type="text" name="username" value="" requied /><input type="submit" value="Найти"></p>
{% endblock %}

.py file:

@app.route("/profile", methods=["POST", "GET"])
def profile():
    if 'userLogged' not in session:
        return redirect(url_for('login'))
    else:
        if request.method == 'POST':
            con = sqlite3.connect("users.sqlite")
            cur = con.cursor()
            search = cur.execute("""SELECT * FROM persons""")
            for el in search:
                if el[1] == request.form['username']:
                    print("SHALOM")
                    return redirect("person")

        return render_template('profile.html', menu=menu)

Error - werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand. KeyError: 'username'