The postdata parameter that is passed to the BeforeNavigate2 event may contain incomplete data in Internet Explorer 6

When you submit a form from a Web page that is displayed in a Web browser control application that sinks the BeforeNavigate2 event, the postdata parameter that is passed to the BeforeNavigate2 event may contain incomplete data.

This problem may occur if either one of the following conditions is true:

• The form contains a FileUpload element.
• The form has the content type "multipart/form-data" header.

Microsoft has confirmed that this is a problem in Microsoft Internet Explorer 6.

When a form uses the content type "multipart/form-data," the POST data is created in an array in multi-part MIME format. All the data for the elements up to the FileUpload element is stored in one element of the array. The binary contents of the file are stored in the next element of the array. The data for the elements after the FileUpload element is stored in a later element of the array.

When Internet Explorer passes the postdata parameter to the BeforeNavigate2 event, Internet Explorer only passes the first array element. This array element only contains the data up to the FileUpload element. Therefore, the postdata parameter that Internet Explorer passes to the BeforeNavigate2 event contains incomplete data.