So, ical4android expects uid2445 on API level 17+, but in your case, you have Android 4.2.2, but the column isn’t there. You can try to reset your calendar storage (Settings / Apps / Calendar Storage / Delete data) and add the DAVdroid account again. If it still doesn’t work, I’d suggest to use another firmware which behaves as documented (either a firmware update from your manufacturer, if available, or a custom ROM like CyanogenMod).
Not all content syncs
I use a Nextcloud server to sync my contacts/calendar/tasks with Thunderbird on my laptop and Davx5 on my Android 10 smartphone.
Each contact is allocated a category in Thunderbird, the category appears in Nextcloud, but not on my phone.
Can anyone suggest what might be going on
@pewe Which contact group method do you use? Which one did you set in DAVx5 (account settings / contact group method)?
Thanks - I changed that setting and it is now working