Hi!
On the device page https://openwrt.org/toh/d-link/dir-878_a1 it say "OpenWrt V24+ can be installed via the stock firmware...".
Sorry for newbie stupid question, but I don't see versions above 23 there?
Thanks in advance!
There is no openwrt 24 for now. Come back in a few months (6+) or use a snapshot.
So is it a misprint in the article? Or a strong commitment? 
it just means snapshots & next version you can install from the normal dlink firmware upgrade page
but v23 and older you still need to use the recover interface