When moving from android to iphone and keeping Nextcloud as my calendar and contacts sync, hundreds of contacts would not sync.

fix _contacts.py

import pathlib

# pip install vobject
import vobject


input_file = pathlib.Path("cache/contacts-bad.vcf")
output_file = pathlib.Path("cache/contacts-fixed.vcf")

with input_file.open() as input_fo, output_file.open('w', newline="") as output_fw:
    for item in vobject.readComponents(input_fo):
        output_fw.write(item.serialize())