I am searching for this answer for like 2 hours now.

Is it possible to save newly created workbook as csv or csv-utf8 file ???

I know how to save it as xlsx xlsm etc, but csv does not seem to work.

Save part of the Code below:

```
wb = xw.Book()
wb.sheets.add('Ceny')
wb.sheets['Ceny'].range('A1').options(index=False, header=False).value = mainDF
wb.save(r'D:\mainDF.csv')
wb.app.quit()

```

Error I am getting:

```
file_format = ext_to_file_format[target_ext]
KeyError: '.csv'

```

I was reading that I am supposed to sepcify file format and maybe use saveas ?? but I have no idea how to do it :(