The request is not supported. Encrypting an Image in ASP.net - asp.net

Question

I am trying to create a simple encryption program with visual basic on visual studio. My program is to encrypt an image then decrypt it. The system is saying that the request is not supported. As a note I am just learning about encrypting and not sure if I am even doing this correctly. Any comments or help would be much appreciated.
Error is from this: File.Encrypt(FileName)
if my encrypt is creating an error then my decrypt will most likely as well
Imports System
Imports System.IO
Imports System.Security.Cryptography
Partial Class _Default
Inherits System.Web.UI.Page
'My Encrypt button that takes the file from my FileUpload tool and Encrypts it, then outputs on my label
'that the file was successfully encrypted
Protected Sub EncryptButton_Click(sender As Object, e As EventArgs) Handles EncryptButton.Click
Dim FileName As String = FileUpload1.FileName
File.Encrypt(FileName)
Label1.Text = "Encrypt" + FileName
End Sub
'My Decrypt button that takes the file from my FileUpload tool and Encrypts it, then outputs on my label
'that the file was successfully encrypted
Protected Sub DecryptButton_Click(sender As Object, e As EventArgs) Handles DecryptButton.Click
Dim FileName As String = FileUpload1.FileName
File.Decrypt(FileName)
Label1.Text = "Decrypt" + FileName
End Sub
'Load page that will display a success output on the label if the upload is completed
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
If FileUpload1.HasFile = True Then
Label1.Text = "Success"
Else
Label1.Text = "Failed"
End If
End Sub
Protected Sub CustomValidator1_ServerValidate(source As Object, args As ServerValidateEventArgs) Handles CustomValidator1.ServerValidate
'Verify the control has a file
If Not FileUpload1.HasFile Then
CustomValidator1.ErrorMessage = "A file is required in order to proceed"
args.IsValid = False
Else
'next 2 lines are all one line
Dim ext As String =
System.Web.VirtualPathUtility.GetExtension(FileUpload1.FileName).ToUpper()
If Not ext = ".GIF" And Not ext = ".JPG" And Not ext = ".PNG" Then
'next 2 lines are all one line
CustomValidator1.ErrorMessage = String.Concat("Invalid file type '", ext, "' -must be .gif or .jpg or .png to continue")
args.IsValid = False
Else
args.IsValid = True
End If
End If
End Sub
End Class

Answer 1

I searched for "System.IO.IOException" and found Troubleshooting Exceptions: System.IO.IOException which states
Make sure the file and directory exist.
Then looking at the code:
Dim FileName As String = FileUpload1.FileName
I see that there is no directory specified for the file. So, you need to use Path.Combine so that you can give File.Encrypt the full filename including the path.
(There is no indiction in the posted code of which directory the uploaded file is in, so I can't help further with that. It could be that FileUpload1 has a property which gives that.)