how to convert xlsx to xls

[Krszt]

I have a bunch of .xlsx files that I want to convert to xls, because my code works only with .xls
Could you suggest something for me?

[Larz60+]

one method would be to open in excel as .xlsx and save as .xls
Hard to say otherwise since you haven't posted your code

[Krszt]

Yes, but I have more than 100 xlsx so it would keep more times. I thought it would be possible to have a new program that save all xlsx to xls.

[Larz60+]

the following code can convert all (requires python 3.6 or newer, and openpyxl):
Replace '.' in line 7 with your path to xlsx files .xls files will be in same directory
You should probably remove the print statement. I only left it so you can see what's there

from pathlib import Path
import openpyxl
import os

# get files
os.chdir(os.path.abspath(os.path.dirname(__file__)))
pdir = Path('.')
filelist = [filename for filename in pdir.iterdir() if filename.suffix == '.xlsx']

for filename in filelist:
    print(filename.name)

for infile in filelist:
    workbook = openpyxl.load_workbook(infile)
    outfile = f"{infile.name.split('.')[0]}.xls"
    workbook.save(outfile)