flask-sqlalchemy

I get the following error whenever I try to send data to a Flask form: Method Not Allowed The method is not allowed for the ... <input type="submit" class="btn btn-success" value="Отправить"> </form> </div> {% endblock %}

There are two tables - the table of (musical) instruments and the table of notes. They are correlated as many to many. The li ... task. It remains only to try it and rewrite it to sqlalchemy. As soon as there is time, I will do it and post it here result.