Server.GetLastError

[VK]

Hello,

I am trying to get the last occured error via the
following code:

Sub Page_Load(...)
Dim zero As Integer = 0
Try
Dim err As Integer = 10 / zero
Catch ex As Exception
End Try

Response.write(Server.GetLastError.Message)
End Sub

However the above code always throws an error at the
response.write line with:

Object reference not set to an instance of an object.

Anybody knows why this is happening?

 

[Brad]

Well, first off 10/0 will not throw an error. I also assume you must have
Option Strict Off or your code would not even compile: err would need to be
dimmed as a double or you would need ctype(10/zero, double) for code to
compile.

I think GetLastError only returns the last unhandled error, during the
current context, and I think the page's Page_Error event or global.asax
Application_Error event has to be raised to access it. Once one of those
events is raised Server.GetLastError is available anywhere in your
code...for the remainder of the current context / request

Example:

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Dim zero As Integer = 0
Dim err As Double = 10 / CType("x", Integer)
End Sub

Private Sub Page_Error(ByVal sender As Object, ByVal e As System.EventArgs)
Handles MyBase.Error
Response.Write(Server.GetLastError.Message)
End Sub

Or since it's now available anywhere, you could also do something like this:

Private Sub Page_Error(ByVal sender As Object, ByVal e As System.EventArgs)
Handles MyBase.Error
Server.Transfer("error.aspx")
End Sub

And then in error.aspx

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Response.Write(Server.GetLastError.Message)
End Sub

 

[William F. Robertson, Jr.]

Since you are catching the exception, it is no longer an error.

bill

 

[Matt Berther]

Hello VK,

If this code would generate an error (which it wont as detailed by Brad),
you're swallowing it anyways. You need to remove the try/catch.