NetworkManager exit status 1

Recently reinstalled NextDNS on a RPi4 64bit and came across this error:

# nextdns activate
Error: NetworkManager resolver management: exit status 1

It seems like NextDNS was actually running, but just throwing an error when running nextdns activate. Restarting did seem to work without throwing any error.

The logs showed the same error:

Dec 20 14:06:20 tyr nextdns[5753]: Starting NextDNS 1.38.0/linux on :53
Dec 20 14:06:20 tyr nextdns[5753]: Listening on TCP/:53
Dec 20 14:06:20 tyr nextdns[5753]: Starting mDNS discovery
Dec 20 14:06:20 tyr nextdns[5753]: Listening on UDP/:53
Dec 20 14:06:21 tyr nextdns[5753]: Connected 45.90.28.0:443 (con=13ms tls=58ms, TCP, TLS13)
Dec 20 14:06:21 tyr nextdns[5753]: Connected 185.18.148.91:443 (con=12ms tls=28ms, TCP, TLS13)
Dec 20 14:06:21 tyr nextdns[5753]: Switching endpoint: https://dns.nextdns.io#185.18.148.91,2a04:b80:1:30::2
Dec 20 14:06:25 tyr nextdns[5753]: Setting up router
Dec 20 14:06:25 tyr nextdns[5753]: Activating
Dec 20 14:06:25 tyr nextdns[5753]: Activate: NetworkManager resolver management: exit status 1

The solution was (as root):

apt install network-manager resolvconf -y
systemctl enable NetworkManager
systemctl start NetworkManager
nextdns activate

Looks like, instead of resolvconf, openresolv was installed.

First time I heard about openresolv; usually resolvconf is the default. Not entirely sure if this was the culprit (and NetworkManager not being started) but the errors are now gone.