Interop - save UTF-8 .csv to .xlsx - vb.net

Question

Using Excel.Interop I want to open a .txt or .csv file and save it as an excel file. Most of the times this simple code works:
Dim Exl As New Excel.Application()
Dim wb1 As Excel.Workbook = Exl.Workbooks.Open("C:\MyFile.txt", Format:=4)
wb1.SaveAs("C:\MyFile.xlsx", FileFormat:=Excel.XlFileFormat.xlOpenXMLWorkbook)
wb1.Close()
Exl.Quit()
However sometimes the .txt/.csv that is being converted contains special characters like ü, ä or ö - and in these cases these characters are replaced by other characters in the resulting excel file.
The problem seems to be that the input files are UTF-8 encoded. So I tried to change the second line to
Dim wb1 As Excel.Workbook = Exl.Workbooks.Open("C:\MyFile.txt", Format:=4, Origin:=61005)
which doesn't work either.
Another option that I came across was to simply use OpenText instead of Open, however now I get an exception:
Dim wb1 As Excel.Workbooks
wb1.OpenText("C:\MyFile.txt")
Exl.wb1.SaveAs("C:\MyFile.xlsx", FileFormat:=Excel.XlFileFormat.xlOpenXMLWorkbook)
wb1.Close()
Exl.Quit()
Thank you for any help!

Answer 1

The Origin parameter of the Workbooks.Open Method must be a value from the XlPlatform enumeration;
Name Value Description
xlMacintosh 1 Macintosh
xlMSDOS 3 MS-DOS
xlWindows 2 Microsoft Windows
Your code:
wb1 As Excel.Workbook = Exl.Workbooks.Open("C:\MyFile.txt", Format:=4, Origin:=61005)
is trying to specify a code page identifier. This is supported by the Origin parameter of the Workbooks.OpenText Method. Additionally, you have a transcription error in the identifier value; it should be 65001 not 61005.
Here is an example using then OpenText method.
Sub Example()
Const UTF8CodePage As Int32 = 65001
Dim app As New Excel.Application
app.Visible = True
Dim filePath As String = "F:\TestUTF_8Quoted.txt"
Dim fi As New IO.FileInfo(filePath)
app.Workbooks.OpenText(Filename:=filePath, Semicolon:=True, Origin:=UTF8CodePage, TextQualifier:=Excel.XlTextQualifier.xlTextQualifierDoubleQuote)
Dim wb As Excel.Workbook = app.Workbooks.Item(fi.Name)
wb.Close(False)
app.Quit()
End Sub