Overflow Runtime error 6

[ScabbyDog]

My code below won't run. Is it because there is about 35000 rows of data used and it can't handle finding the last used row that it gives me the error?

    Sub Transfer()
Dim LastRow As Integer

LastRow = Worksheets("Master").Range("A40000").End(xlUp).Row
'''LastRow = Worksheets("Master").UsedRange.Rows.Count

Sheets("Sheet3").Range("A2:Z250").Copy
Worksheets("Master").Range("A" & LastRow + 1 & ":N" & LastRow + 1).PasteSpecial _
    Paste:=xlPasteValues
    
End Sub