Sub Import()
Application.ScreenUpdating = False
Dim Quelle As Object, Ziel As Object
Dim Datei As String
Dim Blatt As Worksheet
Set Blatt = ThisWorkbook.Worksheets("Tabelle1")
Blatt.Unprotect Password:="test"
On Error GoTo Fehler
Datei = Application.GetOpenFilename("Excel-Dateien(*.xlsx),*xlsx")
Workbooks.Open Filename:=Datei
Set Quelle = ActiveWorkbook.Worksheets(1)
Set Ziel = ThisWorkbook.Worksheets("Tabelle1")
Quelle.UsedRange.Copy Ziel.Cells(1, 1)
ActiveWorkbook.Close
Set Quelle = Nothing
Set Ziel = Nothing
Exit Sub
Fehler:
Set Quelle = Nothing
Set Ziel = Nothing
MsgBox "FehlerNr.: " & Err.Number & vbNewLine & vbNewLine _
& "Beschreibung: " & Err.Description _
, vbCritical, "Fehler"
Blatt.Protect Password:="test"
Set Blatt = Nothing
End Sub