I just upgraded to Pi-hole v6, hooray!
Alas:
The web UI led me to sudo pihole -d, which spit out lots of output, and this:
Your debug token is: https://tricorder.pi-hole.net/ubxnGTCf/
Hopefully someone can help me? 
Edit: Since the error is called "DNS Server failure", I assume it might have something to do with my unbound setup...? But it doesn't look like my configuration is wrong?
erik@MinipcLG2:~$ cat /etc/unbound/unbound.conf.d/pi-hole.conf
server:
# If no logfile is specified, syslog is used
# logfile: "/var/log/unbound/unbound.log"
verbosity: 0
interface: 127.0.0.1
port: 5335
do-ip4: yes
do-udp: yes
do-tcp: yes
# May be set to yes if you have IPv6 connectivity
do-ip6: no
# You want to leave this to no unless you have *native* IPv6. With 6to4 and
# Terredo tunnels your web browser should favor IPv4 for the same reasons
prefer-ip6: no
# Use this only when you downloaded the list of primary root servers!
# If you use the default dns-root-data package, unbound will find it automatically
#root-hints: "/var/lib/unbound/root.hints"
# Trust glue only if it is within the server's authority
harden-glue: yes
# Require DNSSEC data for trust-anchored zones, if such data is absent, the zone becomes BOGUS
harden-dnssec-stripped: yes
# Don't use Capitalization randomization as it known to cause DNSSEC issues sometimes
# see https://discourse.pi-hole.net/t/unbound-stubby-or-dnscrypt-proxy/9378 for further details
use-caps-for-id: no
# Reduce EDNS reassembly buffer size.
# IP fragmentation is unreliable on the Internet today, and can cause
# transmission failures when large DNS messages are sent via UDP. Even
# when fragmentation does work, it may not be secure; it is theoretically
# possible to spoof parts of a fragmented DNS message, without easy
# detection at the receiving end. Recently, there was an excellent study
# >>> Defragmenting DNS - Determining the optimal maximum UDP response size for DNS <<<
# by Axel Koolhaas, and Tjeerd Slokker (https://indico.dns-oarc.net/event/36/contributions/776/)
# in collaboration with NLnet Labs explored DNS using real world data from the
# the RIPE Atlas probes and the researchers suggested different values for
# IPv4 and IPv6 and in different scenarios. They advise that servers should
# be configured to limit DNS messages sent over UDP to a size that will not
# trigger fragmentation on typical network links. DNS servers can switch
# from UDP to TCP when a DNS response is too big to fit in this limited
# buffer size. This value has also been suggested in DNS Flag Day 2020.
edns-buffer-size: 1232
# Perform prefetching of close to expired message cache entries
# This only applies to domains that have been frequently queried
prefetch: yes
# One thread should be sufficient, can be increased on beefy machines. In reality for most users running on small networks or on a single machine, it should be unnecessary to seek performance enhancement by increasing num-threads above 1.
num-threads: 1
# Ensure kernel buffer is large enough to not lose messages in traffic spikes
so-rcvbuf: 1m
# Ensure privacy of local IP ranges
private-address: 192.168.0.0/16
private-address: 169.254.0.0/16
private-address: 172.16.0.0/12
private-address: 10.0.0.0/8
private-address: fd00::/8
private-address: fe80::/10
Anyway, I saw:
So I ran sudo PIHOLE_SKIP_OS_CHECK=true pihole -r gain. I'll see how it goes after the new update.
Another issue: I can't access my openHAB UI anymore, which should be http://192.168.1.9:8080/. I assume Pi-hole "took over" that port, or something like that?
Some searching, led me to confirmation:
erik@MinipcLG2:~$ sudo netstat -tulpe --numeric-ports | grep 8080
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN pihole 18412 2398/pihole-FTL
tcp6 0 0 [::]:8080 [::]:* LISTEN pihole 18414 2398/pihole-FTL
Is there another port I can "refer" pihole to?
Thanks in advance for anyone's help!
