Algernon83 suggestion fixed it for me. You have no idea how aggravating this was, wondering what the issue was and no time to troubleshoot. HAHA, reinstalled davdroid and rebooted OC server and was about to try some more severe stuff. Thanks.
Davdroid fails since Android 7.1
I upgraded to Android 7.1 today and since then DavDroid fails to synchronize with NextCloud. Here’s my debug log: https://git.project-insanity.org/snippets/10
This is not related to updating Android. Please follow up at https://forums.bitfire.at/topic/1259/rev-must-not-appear-more-than-once-in-a-vcard-component/