add to app/auth/routes.py

routes.py

@bp.route("/reset_password/<token>/<int:user_id>", methods=["GET", "POST"])
def reset_password(token, user_id):
    if current_user.is_authenticated:
        return redirect(url_for("main.index"))

    user = User.validate_reset_password_token(token, user_id)
    if not user:
        return render_template(
            "auth/reset_password_error.html", title="Reset Password error"
        )

    form = ResetPasswordForm()
    if form.validate_on_submit():
        user.set_password(form.password.data)
        db.session.commit()

        return render_template(
            "auth/reset_password_success.html", title="Reset Password success"
        )

    return render_template(
        "auth/reset_password.html", title="Reset Password", form=form
    )