WebUI suddenly went down, opening the page would show a message that TrueNAS is not avialable or offline. Ping was working, VMs and jails were accessible, ssh was working. Restarting nginx didn't solve the issue.
After triggering a restart from ssh, I have see the notification about system core files for the first time. I am on TrueNAS 12.0 U2. I have never seen this before nor faced this issue.
System core file compressed and attached. /var/log/messages before the restart showed a bunch of the below, I am not sure if those are relevant
ConnectionRefusedError: [Errno 61] Connection refused
Feb 21 13:17:33 Orion 1 2021-02-21T13:17:33.114002+02:00 Orion.makhlouta collectd 2189 - - Traceback (most recent call last):
File "/usr/local/lib/collectd_pyplugins/disktemp.py", line 62, in read
with Client() as c:
File "/usr/local/lib/python3.8/site-packages/middlewared/client/client.py", line 281, in _init_
File "/usr/local/lib/python3.8/site-packages/middlewared/client/client.py", line 124, in connect
rv = super(WSClient, self).connect()
File "/usr/local/lib/python3.8/site-packages/ws4py/client/_init_.py", line 216, in connect