FileUpload and UpdatePanel: ScriptManager.RegisterPostBackControl works the second time

Question

I\'m developing an ASP.NET application with C# and Visual Studio 2008 SP1. I\'m using WebForms.

I have an ASPX page with two UpdatePanels, one on the left that holds

Answer 1

For me this solution worked:

add Page.Form.Attributes.Add("enctype", "multipart/form-data");

The enctype attribute is missing on the first postback.

http://adamnoffie.blogspot.com/2007/10/file-upload-not-working-on-first.html