Error creating window handle

[JA12]

I'm having a problem with "Showing" one particular form.

I have a dozen forms all are children of an MDI form.

One particular form always fails on the first "Show" with the error "Error creating window handle", then the second time I load it, the "Show" succeeds.

I'm first attaching all the forms to the MDI form

        frmAdmin.MdiParent = Me
        frmAdmin.Dock = DockStyle.Fill
        frmAdmin.Hide()

Then when the time comes to Show the form, I call a Subroutine to do the job:

    Public Sub LoadFormAndRefresh(ByRef vForm As Form)
        Const C_PROC_NAME = "LoadFormAndRefresh"
        Try
            ' hide everything
            For Each oForm As Form In Me.MdiChildren
                oForm.Hide()
            Next
            Me.Refresh()
            vForm.Show()                  <------------------- fails here
            Me.Refresh()
        Catch ex As Exception
            If modGlobals.gDebug Then Console.Write(CODE_MODULE, C_PROC_NAME & ": " & ex.Message)
            oERR.LogFileError(vModule:=CODE_MODULE,
                              vRoutine:=C_PROC_NAME,
                              vEX:=ex,
                              vLogLevel:=clsLogFile.LoggingLevel.LogEverything)
            If modGlobals.gDebug Then Stop
        End Try
    End Sub

The code steps through the frmAdmin_Load subroutine with no errors then fails when back in the MDI routine.

Any ideas?

[jmcilhinney]

Have a look at the StackTrace of the exception. It will tell you where the actual error occurs. Almost certainly it's in an event handler that is executed due to a property that you have set in the designer. For example, if you have set the Text of a TextBox then the TextChanged event will be raised and the event handler might assume that something has happened that hasn't at that stage.

[JA12]

These are the Exception details for the error

Exception Details: 
	HResult: -2147467259
	Message: Error creating window handle.
	String: System.ComponentModel.Win32Exception (0x80004005): Error creating window handle.
   at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp)
   at System.Windows.Forms.Control.CreateHandle()
   at System.Windows.Forms.Form.CreateHandle()
   at System.Windows.Forms.Control.get_Handle()
   at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
   at System.Windows.Forms.Control.Show()
   at WindowsApplication1.mdiMain.LoadFormAndRefresh(Form& vForm) in C:\Users\usr\Documents\Visual Studio 2012\Projects\WindowsApplication1\WindowsApplication1\mdiMain.vb:line 189
	Source: System.Windows.Forms

[kaliman79912]

are you using the default instance of the form?

[Niya]

Oh man oh man. I think MDIs are glitched in .Net. You wouldn't believe the amount of weird and unexplainable problems like this I've come across when using them. It might be something you're doing wrong but my experience tells me its more than likely another glitch. You should try to find out what conditions cause the error(bet my left foot it'll be weird conditions too) and work around them.

[jmcilhinney]

Hmmm... is there an InnerException?

[JA12]

I couldn't find an InnerException, but the following (very dirty) bit of code works...

        Try
            frmAdmin.Show()
        Catch ex As Exception
            frmAdmin.Show()
        End Try

The first attempt always fails then the second attempt always seems to work.

[kaliman79912]

Try creating a new instance (do that always)

Using newForm as New frmAdmin
    newForm.Show()
End Using

[JA12]

That new form business just make things worse. Nothing was loaded, all the forms load then vanish leaving an empty MDI container. The way I had it was better, even with the dirty workaround.

[kaliman79912]

ok, do without the Using -End Using, but do not use the default instance.