Why am i getting error BC42104 Variable is used before it is assigned?

Question

I can't figure out why i keep getting this warning message for the following variables: xlApp, xlWorkBooks, xlWorkSheet, xlWorkSheets, xlWorkBook.

    Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click

    'PRE-PROCESSING VALIDATIONS
    Button2.Visible = False
    Button6.Visible = False

    If perennialcounter + annualcounter >= 6 Then
        MsgBox("No more files can be loaded")
        GoTo BypassThis
    End If

    'select and open file

    'file selection box and error handling for no file selected/cancel button
    TempOpenFileDialog.Title = "Select an Input File"
    If Testing = True Then
        TempOpenFileDialog.InitialDirectory = TestingFileDefaultDirectory
    Else
        TempOpenFileDialog.InitialDirectory = TallySheetOrderFileDefaultDirectory
    End If
    TempOpenFileDialog.Multiselect = False
    TempOpenFileDialog.ShowDialog()
    tempfilepath = TempOpenFileDialog.FileName()
    tempfile = Path.GetFileName(tempfilepath)
    If tempfilepath = "" Then
        GoTo BypassThis
    End If

    'open file
    Dim xlApp As Excel.Application = Nothing
    Dim xlWorkBooks As Excel.Workbooks = Nothing
    Dim xlWorkBook As Excel.Workbook = Nothing
    Dim xlWorkSheets As Excel.Worksheets = Nothing
    Dim xlWorkSheet As Excel.Worksheet = Nothing
    xlApp = New Excel.Application
    xlApp.DisplayAlerts = False
    xlWorkBooks = xlApp.Workbooks
    xlWorkBooks.Open(tempfilepath)
    If Testing = True Then
        xlApp.Visible = True
    Else
        xlApp.Visible = False
    End If
    xlWorkBooks(tempfile).Activate()
    xlWorkSheet = xlApp.ActiveWorkbook.ActiveSheet

    'lots and lots of code...
bypassthis:
    'close excel (save) and release objects
    xlhwnd = xlApp.Hwnd    '<------ warning here
    ProcIDxl = 0
    xproc = Process.GetProcessById(ProcIDxl)
    GetWindowThreadProcessId(xlhwnd, ProcIDxl)

    xlWorkBooks(tempfile).Close(True)    '<------ warning here
    xlApp.Application.Quit()

    GC.Collect()
    GC.WaitForPendingFinalizers()

    releaseObject(xlWorkSheet)    '<------ warning here
    releaseObject(xlWorkSheets)    '<------ warning here
    releaseObject(xlWorkBook)    '<------ warning here
    releaseObject(xlWorkBooks)
    releaseObject(xlApp)

    xlWorkSheet = Nothing
    xlWorkSheets = Nothing
    xlWorkBook = Nothing
    xlWorkBooks = Nothing
    xlApp = Nothing


    'show/reshow buttons
    If perennialcounter + annualcounter > 0 Then
        Button6.Visible = True
        Button6.Text = "Process"
    End If
    Button2.Visible = True
    ProgressBar7.Visible = False
    ProgressBar8.Visible = False
End Sub

There is nothing in the code that would push it out of the sub or skip the line where the first error is. Any assistance is appreciated.

Answer 1

To fix this, you should repeat your test on tempfilepath in the bypassthis block...

bypassthis:

If tempfilepath <> "" Then

'close excel (save) and release objects
    xlhwnd = xlApp.Hwnd    '<------ warning here
    ProcIDxl = 0
    xproc = Process.GetProcessById(ProcIDxl)
    GetWindowThreadProcessId(xlhwnd, ProcIDxl)

    xlWorkBooks(tempfile).Close(True)    '<------ warning here
    xlApp.Application.Quit()

    GC.Collect()
    GC.WaitForPendingFinalizers()

    releaseObject(xlWorkSheet)    '<------ warning here
    releaseObject(xlWorkSheets)    '<------ warning here
    releaseObject(xlWorkBook)    '<------ warning here
    releaseObject(xlWorkBooks)
    releaseObject(xlApp)

    xlWorkSheet = Nothing
    xlWorkSheets = Nothing
    xlWorkBook = Nothing
    xlWorkBooks = Nothing
    xlApp = Nothing

End If

As Alex B. mentioned in the comments, please be careful with GoTo - it is what caused your issue.