There is a problem in F-Droid 0.101-alpha1 with permission for SDK > 23. It even prevented updating F-Droid itself to a version that has the fix. So the fix here is to uninstall F-Droid and reinstall it again from website apk download. Then you can install/update DAVDroid to the newest version.
"rQ" added to every addressbook-name? Why?
while adding the contacts from Nextcloud to my mobile with davdroid, “rQ” is added always to the addressbook-name.
Is anybody aware of this?
Please see https://forums.bitfire.at/topic/1674/what-is-the-2-letters-after-the-account-name-for-address-books and the links there (especially the manual)