Asp.net files are uploaded using the HTML file control. When using the master page master, change the form's enctype = multipart/form-data method.

In many cases, for example, when multiple files are on the ship, most of us use the HTML file control. It happens that we use the master page master, and the form is on the master page, in this case, the Upload File's enctype = "multipart/form-Data" cannot be directly set in the master page.

Solution:

The original master page does not need to be changed. On the Upload File page, set the form attribute of the master file on the master page, and addCode

Htmlform form1 = (htmlform) master. findcontrol ("Form1"); Form1.enctype="Multipart/form-Data";