Lxc list struck after upgrading to lxd 4.0

,
$ ps fauxww | grep lxd
zhijli   11781  0.0  0.0  16988   988 pts/1    S+   23:21   0:00      \_ grep --colour=auto lxd
root     11049  0.1  0.1 1395052 36792 ?       Ssl  22:55   0:01 /usr/sbin/lxd --group lxd --logfile /var/log/lxd/lxd.log

$ sudo tail -f /var/log/lxd/lxd.log
t=2020-05-17T23:21:51+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=5" 
t=2020-05-17T23:21:52+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=6" 
t=2020-05-17T23:21:53+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=7" 
t=2020-05-17T23:21:54+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=8" 
t=2020-05-17T23:21:55+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=9" 
t=2020-05-17T23:21:56+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=10" 
t=2020-05-17T23:21:57+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=11" 
t=2020-05-17T23:22:00+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=0" 
t=2020-05-17T23:22:01+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=1" 
t=2020-05-17T23:22:01+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=2" 
t=2020-05-17T23:22:02+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=3" 
t=2020-05-17T23:22:03+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=4" 
t=2020-05-17T23:22:04+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=5" 
t=2020-05-17T23:22:05+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=6" 
t=2020-05-17T23:22:06+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=7" 
t=2020-05-17T23:22:07+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=8" 
t=2020-05-17T23:22:08+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=9" 
t=2020-05-17T23:22:09+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=10" 
t=2020-05-17T23:22:10+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=11" 
t=2020-05-17T23:22:13+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=0" 
t=2020-05-17T23:22:13+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=1" 
t=2020-05-17T23:22:13+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=2" 
t=2020-05-17T23:22:14+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=3" 
t=2020-05-17T23:22:15+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=4" 
t=2020-05-17T23:22:16+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=5" 
t=2020-05-17T23:22:17+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=6" 
t=2020-05-17T23:22:18+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=7" 
t=2020-05-17T23:22:19+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=8" 
t=2020-05-17T23:22:20+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=9" 
t=2020-05-17T23:22:21+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=10" 
t=2020-05-17T23:22:22+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=11" 
t=2020-05-17T23:22:25+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=0" 
t=2020-05-17T23:22:25+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=1" 
t=2020-05-17T23:22:26+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=2" 
t=2020-05-17T23:22:27+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=3" 
t=2020-05-17T23:22:28+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=4" 
t=2020-05-17T23:22:29+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=5" 
t=2020-05-17T23:22:30+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=6" 
t=2020-05-17T23:22:31+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=7" 
t=2020-05-17T23:22:32+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=8" 
t=2020-05-17T23:22:33+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=9" 
t=2020-05-17T23:22:34+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=10" 
t=2020-05-17T23:22:35+0800 lvl=warn msg="Dqlite: no known leader address=1 attempt=11" 
t=2020-05-17T23:22:36+0800 lvl=warn msg="Failed connecting to global database (attempt 130): failed to create dqlite connection: no available dqlite leader server found"

I fixed by myself:

mv /var/lib/lxd/database /var/lib/lxd/database.bak

/etc/init.d/lxd restart

@freeekanayaka

Seeing the same thing with a fresh deploy of lxd 4.4:

Aug 10 21:53:37 armaldo lxd.daemon[16939]: t=2020-08-10T21:53:37+0000 lvl=warn msg=“Dqlite: attempt 8: server 1: no known leader”
Aug 10 21:53:38 armaldo lxd.daemon[16939]: t=2020-08-10T21:53:38+0000 lvl=warn msg=“Dqlite: attempt 9: server 1: no known leader”
Aug 10 21:53:39 armaldo lxd.daemon[16939]: t=2020-08-10T21:53:39+0000 lvl=warn msg=“Dqlite: attempt 10: server 1: no known leader”
Aug 10 21:53:40 armaldo lxd.daemon[16939]: t=2020-08-10T21:53:40+0000 lvl=warn msg=“Dqlite: attempt 11: server 1: no known leader”
…skipping…
Aug 11 00:44:11 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:11+0000 lvl=warn msg=“Dqlite: attempt 7: server 1: no known leader”
Aug 11 00:44:12 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:12+0000 lvl=warn msg=“Dqlite: attempt 8: server 1: no known leader”
Aug 11 00:44:13 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:13+0000 lvl=warn msg=“Dqlite: attempt 9: server 1: no known leader”
Aug 11 00:44:14 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:14+0000 lvl=warn msg=“Dqlite: attempt 10: server 1: no known leader”
Aug 11 00:44:15 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:15+0000 lvl=warn msg=“Dqlite: attempt 11: server 1: no known leader”
Aug 11 00:44:18 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:18+0000 lvl=warn msg=“Dqlite: attempt 0: server 1: no known leader”
Aug 11 00:44:18 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:18+0000 lvl=warn msg=“Dqlite: attempt 1: server 1: no known leader”
Aug 11 00:44:18 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:18+0000 lvl=warn msg=“Dqlite: attempt 2: server 1: no known leader”
Aug 11 00:44:19 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:19+0000 lvl=warn msg=“Dqlite: attempt 3: server 1: no known leader”
Aug 11 00:44:20 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:20+0000 lvl=warn msg=“Dqlite: attempt 4: server 1: no known leader”
Aug 11 00:44:21 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:21+0000 lvl=warn msg=“Dqlite: attempt 5: server 1: no known leader”
Aug 11 00:44:22 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:22+0000 lvl=warn msg=“Dqlite: attempt 6: server 1: no known leader”
Aug 11 00:44:23 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:23+0000 lvl=warn msg=“Dqlite: attempt 7: server 1: no known leader”
Aug 11 00:44:24 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:24+0000 lvl=warn msg=“Dqlite: attempt 8: server 1: no known leader”
Aug 11 00:44:25 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:25+0000 lvl=warn msg=“Dqlite: attempt 9: server 1: no known leader”
Aug 11 00:44:26 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:26+0000 lvl=warn msg=“Dqlite: attempt 10: server 1: no known leader”
Aug 11 00:44:27 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:27+0000 lvl=warn msg=“Dqlite: attempt 11: server 1: no known leader”
Aug 11 00:44:30 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:30+0000 lvl=warn msg=“Dqlite: attempt 0: server 1: no known leader”
Aug 11 00:44:30 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:30+0000 lvl=warn msg=“Dqlite: attempt 1: server 1: no known leader”
Aug 11 00:44:31 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:31+0000 lvl=warn msg=“Dqlite: attempt 2: server 1: no known leader”
Aug 11 00:44:32 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:32+0000 lvl=warn msg=“Dqlite: attempt 3: server 1: no known leader”
Aug 11 00:44:33 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:33+0000 lvl=warn msg=“Dqlite: attempt 4: server 1: no known leader”
Aug 11 00:44:34 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:34+0000 lvl=warn msg=“Dqlite: attempt 5: server 1: no known leader”
Aug 11 00:44:35 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:35+0000 lvl=warn msg=“Dqlite: attempt 6: server 1: no known leader”
Aug 11 00:44:36 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:36+0000 lvl=warn msg=“Dqlite: attempt 7: server 1: no known leader”
Aug 11 00:44:37 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:37+0000 lvl=warn msg=“Dqlite: attempt 8: server 1: no known leader”
Aug 11 00:44:38 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:38+0000 lvl=warn msg=“Dqlite: attempt 9: server 1: no known leader”
Aug 11 00:44:39 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:39+0000 lvl=warn msg=“Dqlite: attempt 10: server 1: no known leader”
Aug 11 00:44:40 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:40+0000 lvl=warn msg=“Dqlite: attempt 11: server 1: no known leader”
Aug 11 00:44:43 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:43+0000 lvl=warn msg=“Dqlite: attempt 0: server 1: no known leader”
Aug 11 00:44:43 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:43+0000 lvl=warn msg=“Dqlite: attempt 1: server 1: no known leader”
Aug 11 00:44:43 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:43+0000 lvl=warn msg=“Dqlite: attempt 2: server 1: no known leader”
Aug 11 00:44:44 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:44+0000 lvl=warn msg=“Dqlite: attempt 3: server 1: no known leader”
Aug 11 00:44:45 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:45+0000 lvl=warn msg=“Dqlite: attempt 4: server 1: no known leader”
Aug 11 00:44:46 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:46+0000 lvl=warn msg=“Dqlite: attempt 5: server 1: no known leader”
Aug 11 00:44:47 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:47+0000 lvl=warn msg=“Dqlite: attempt 6: server 1: no known leader”
Aug 11 00:44:48 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:48+0000 lvl=warn msg=“Dqlite: attempt 7: server 1: no known leader”
Aug 11 00:44:49 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:49+0000 lvl=warn msg=“Dqlite: attempt 8: server 1: no known leader”
Aug 11 00:44:50 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:50+0000 lvl=warn msg=“Dqlite: attempt 9: server 1: no known leader”
Aug 11 00:44:51 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:51+0000 lvl=warn msg=“Dqlite: attempt 10: server 1: no known leader”
Aug 11 00:44:52 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:52+0000 lvl=warn msg=“Dqlite: attempt 11: server 1: no known leader”
Aug 11 00:44:53 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:53+0000 lvl=warn msg="Failed connecting to global database (attempt 830): failed to create dqlite connection: >
Aug 11 00:44:55 armaldo lxd.daemon[16939]: t=2020-08-11T00:44:55+0000 lvl=warn msg=“Dqlite: attempt 0: server 1: no known leader”

Fixed it the same way, except /var/snap/lxd/common/lxd/database and I had to manually kill -9 the lxd processes and then start it again.