Response.Redirect hangs on ASYNC

I have the below code, the execution hangs on Response.Redirect method and the redirection does not takes place
private async void FormToolbar1_CustomClick(object sender, EventArgs e) { if (Page.IsValid) { Task<bool> signUpTask = UserSignUp(); Task<bool>.WhenAll(signUpTask); if (await signUpTask) { Response.Redirect("~/Default.aspx"); } } }