Convert vcards from version 2.1 to version 3.0.
I wrote these scripts to convert contacts exported from an Android 4.x phone and import them into Nextcloud. It worked for me, your mileage may vary.
The scripts are rather simple, they don't cover all differences between 2.1 and 3.0.
vcard2to3.py is the conversion script.
Quickstart:
git clone https://github.com/jowave/vcard2to3.git
cd vcard2to3
./vcard2to3.py your_file.vcf
The output will be a file your_file.vcf.converted.
To show available command-line arguments run:
./vcard2to3.py --help
Merge and sort vcards. With vcard_merge.py you can remove duplicate contacts. The contacts are sorted and merged by FN and duplicate lines within one contact are omitted.
You may have to manually edit the result.