Object reference not set to an instance of an object

Question

Good afternoon,

I have created a little application in VB.net which runs fine on my Windows 10 PC but when i run it on another one i get the following message...

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************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
at Timezone_Client.Form1.Timer1_Tick(Object sender, EventArgs e)
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

This is the first part of the code in my application which i believe it relates to.

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick

    Timer1.Interval = 10000
    timer1.Start()

Can anyone assist me please?

I am a novice, so please bear with me!

Thanks
Simon

Answer 1

Thanks for your reply.

I simply dragged a timer onto the form and then put that code under the Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick event.

Apologies if that's not what you meant!

Thanks
Simon

Answer 2

Hi @Simon Scott ,
Try starting the timer outside the Tick event:

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick  
        ' do something here.  
    End Sub  
  
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click  
        Timer1.Interval = 10000  
        Timer1.Start()  
    End Sub  
    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click  
        Timer1.Stop()  
    End Sub  

Click Button1 to start the timer and Button2 to stop it.
Besides, set ‘Enabled’ property 'false'.

Hope it could be helpful.

Best Regards,
Xingyu Zhao
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Answer 3

Ok, so i think i may have found where the issue is...

I do have the line Dim sString As String = Nothing further up the page within the same sub

Any advice?

Many thanks
Simon

Answer 4

I believe i have fixed this so hold fire on any possible answers :)