systemd target multi-user.target failed, but how to know why?

Question

How can I diagnose the causes of this inactive state ?

# systemctl --type=target --no-pager
UNIT                   LOAD   ACTIVE   SUB    JOB   DESCRIPTION
basic.target           loaded active   active       Basic System
cryptsetup.target      loaded active   active       Local Encrypted Volumes
getty.target           loaded active   active       Login Prompts
local-fs-pre.target    loaded active   active       Local File Systems (Pre)
local-fs.target        loaded active   active       Local File Systems
multi-user.target      loaded inactive dead   start Multi-User System
network-online.target  loaded active   active       Network is Online
network.target         loaded active   active       Network
nss-user-lookup.target loaded active   active       User and Group Name Lookups
...

Answer 1

It hasn't failed yet – the "JOB" column indicates that there is still a 'start' job pending. Check what other units are waiting for startup:

systemctl list-jobs