Excel Application Crash due to Macro - vba

Question

During launching my macro the Excel application is crashed. If I test the macro with an integer the program runs properly (partnumber = 123). If I check with a string the application is crashed. Thus, no error code is visible for me. I assume that there is a type mismatch (but I set Variant for partnumber)
Sub SbIsInCOPexport()
Dim lastRow As Long
Dim i As Long
Dim found As Boolean
Dim partnumber As Variant
i = 1
found = False
partnumber = ActiveCell.Value
Windows("COPexport.xlsx").Activate
lastRow = Sheets(1).Cells.SpecialCells(xlLastCell).Row
Do While i < lastRow + 1
If Cells(i, 6).Value = partnumber Then
found = True
Exit Do
End If
i = i + 1
Loop
If found = True Then
Cells(i, 6).Select
MsgBox ("Searched part number: " & Str(partnumber) & vbNewLine & "Found part number: " _
& ActiveCell.Value & vbNewLine & "Address: " & Cells(i, 6).Address & vbNewLine & vbNewLine & "Test Order: " & _
Cells(i, 2).Value)
Windows("COPexport.xlsx").Activate
Else
MsgBox "Part number is not found in the COP samples!"
Windows("COPexport.xlsx").Activate
End If
End Sub
What can be the root cause?

Answer 1

I don't see any obvious issues, but consider using the .Find method of range object, like so:
Sub SbIsInCOPexport()
Dim partnumber as Variant
Dim rng as Range
Windows("COPexport.xlsx").Activate
partnumber = ActiveCell.Value
Set rng = Columns(6).Find(partnumber) '## Search in column 6 for partnumber
If rng Is Nothing Then
MsgBox "Part number is not found in the COP samples!"
Windows("COPexport.xlsx").Activate
Else
With rng
MsgBox ("Searched part number: " & Str(partnumber) & vbNewLine & _
"Found part number: " & .Value & vbNewLine & _
"Address: " & .Address & vbNewLine & vbNewLine & _
"Test Order: " & .Offset(0,-4).Value) '## Get the value from column 2
End With
End If
End Sub