Display error message from handler in jQuery Uploadify plugin in ASP.Net

How to show a Error message from Handler Page(.ashx) to .aspx page.

i want to show error message on .aspx page from handler page but it is not working. i writing code like below. 

context.Response.StatusCode = 200;
                        context.Response.Write("Please select a valid file format. Allowed formats: .jpg, .jpeg, .png, .gif");