Thanks a lot for completing your answer!
I’ve tried to disable HTTP/2 on my server like this:
server {
# listen 443 ssl http2;
listen 443 ssl;
server_name dav.mydomain.tld;
root /srv/http/sabredav/;
[...]
…but after further investigations today, I oddly found that my server was still considered as HTTP/2 enabled for dav.mydomain.tld… (test of domain with https://tools.keycdn.com/http2-test )
I will try soon to disable http/2 everywhere in nginx, to see if it works, and follow the issue with okhttp.
OK that’s clear. My idea was, that DAVdroid creates e.g. 5 accounts if I select 5 contacts folders. In this way I don’t need to create and configure 5 accounts manually.
DAVdroid is awesome!!!
Please see here: https://forums.bitfire.at/post/7538
Please make sure that your server doesn’t serve any VCard with the questionable REV time format (i.e. apply >the OwnCloud Contacts fix and then correct invalid VCards).
After that, synchronize all contacts again.
Step 2: To do so, unselect the address books in DAVdroid, force sync, wait a bit until the local contacts are empty and sync again.
