Jail stopped working after upgrade to 12.0-U6.1 with utf-8 decoding error

Hi guys,

I just upgraded to TrueNAS-12.0-U6.1 today and after the reboot my jail stopped working with the following error:
" Error: [EFAULT] 'utf-8' codec can't decode byte 0xc2 in position 454: invalid continuation byte "

I tried to start it from the commnd line via iocage and this ist what it threw at me:

Traceback (most recent call last):
File "/usr/local/bin/iocage", line 10, in <module>
sys.exit(cli())
File "/usr/local/lib/python3.9/site-packages/click/core.py", line 764, in _call_
return self.main(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/usr/local/lib/python3.9/site-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/local/lib/python3.9/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/iocage_cli/start.py", line 60, in cli
ioc.IOCage(jail=jail, rc=rc).start(ignore_exception=ignore)
File "/usr/local/lib/python3.9/site-packages/iocage_lib/iocage.py", line 1811, in start
ioc_start.IOCStart(
File "/usr/local/lib/python3.9/site-packages/iocage_lib/ioc_start.py", line 87, in _init_
raise e
File "/usr/local/lib/python3.9/site-packages/iocage_lib/ioc_start.py", line 84, in _init_
self._start_jail_()
File "/usr/local/lib/python3.9/site-packages/iocage_lib/ioc_start.py", line 274, in _start_jail_
self._check_dhcp_or_accept_rtadv_(ipv4=True, enable=wants_dhcp)
File "/usr/local/lib/python3.9/site-packages/iocage_lib/ioc_start.py", line 1471, in _check_dhcp_or_accept_rtadv_
lambda l: not l.strip().startswith('#') and '=' in l, f.readlines()
File "/usr/local/lib/python3.9/codecs.py", line 322, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc2 in position 454: invalid continuation byte

I already tried to boot the box with an older working Kernel like 12.0-U6 o -U5 instead but it didn't solve the issue. So I suppose some config files are messed up. Obviously the utf-8 character encoding in a python script isn't properly set - but as I am not into phython, I am not able to help myself at the moment.

I'd be grateful for a hint.

Best regads

Heinz

p.s.

this is a replica of my post https://www.truenas.com/community/threads/jail-stopped-working-after-upgrade-to-12-0-u6-1-with-utf-8-decoding-error.96741/