I experienced the following rather unhelpful exception at work today.
Padding is invalid and cannot be removed

With a stacktrace something along the following:

System.Security.Cryptography.RijndaelManagedTransform.DecryptData(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount, Byte[]& outputBuffer, Int32 outputOffset, PaddingMode paddingMode, Boolean fLast) +7596702
System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount) +208
System.Security.Cryptography.CryptoStream.FlushFinalBlock() +33
System.Web.Configuration.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, IVType ivType, Boolean useValidationSymAlgo) +225
System.Web.Security.FormsAuthentication.Decrypt(String encryptedTicket) +246

After doing some searching and more or less complex debugging, and resetting the application pool and what not, I find the simple solution.

I had two projects running on my localhost which both used the default cookie name for forms authentication, which then apparently conflicted with each other. Do’h.
But well, problem solved.

I love using the WITH statement in VB.NET/ASP.NET because it eases up on the typing and helps “group together” functionality.
However, I found a fun little something when using the WITH statement, which I wanted to share.

It seems that you can assign a new object reference within a WITH statement to the specific object, however you can’t assign values to said new reference. Strange indeed, but I’m sure there’s some underlying reason.
Here some code to illustrate.

Suppose I have a class:

Private Class Test
        Private m_Text As String

        Public Property TextValue() As String
            Get
                Return m_Text
            End Get
            Set(ByVal value As String)
                m_Text = value
            End Set
        End Property
End Class

Then I have some code which uses this class in a WITH statement:

Dim obj As New Test()
obj.TextValue = "Test"
  For i As Integer = 0 To 10
   With obj
     If Not String.IsNullOrEmpty(.TextValue) Then
          System.Diagnostics.Debug.WriteLine("VALUE: " & .TextValue)
    Else
         System.Diagnostics.Debug.WriteLine("VALUE NOTHING")
    End If
    obj = New Test()
    .TextValue = "test" & i
   End With
Next

When run this provides the output:
VALUE: Test
VALUE NOTHING

And "nothing" for every subsequent run.
So it is possible to assign a new reference to the “obj” object reference, but the assignment of the new TextValue is ignored.

Not that usefull, but fun enough in my book :) (yes, I’m a geek