I am currently updating from 126.96.36.199 to 188.8.131.52. Therefore I downloaded the latest12 from Index of /server/releases and followed the instructions on Upgrade Manually — Nextcloud 12 Server Administration Manual 12 documentation. The update up to call of occ was successful. I loged in as user and I could not see my contacts. Instead I see the attached screen.
If I search for contacts it works and after I used Firefox instead of Chrome also the list of contacts was working…