Errors in logfile

Hi there,

I’m pretty new in HA but loving it so far. Today I took a look at the logfiles and found alot of errors in there. Some pointing me to but I just cannot find the file to investigate it. Does anybody know where to find this file?

2023-01-20 23:37:15.971 ERROR (MainThread) [homeassistant.helpers.event] Error while processing template: Template("{{as_timestamp(strptime(states('sensor.afvalwijzer_papier'),'%d-%m-%Y'))
  |timestamp_custom('%a %d %b')}}")
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/", line 1631, in strptime
    return datetime.strptime(string, fmt)
  File "/usr/local/lib/python3.10/", line 568, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
  File "/usr/local/lib/python3.10/", line 349, in _strptime
    raise ValueError("time data %r does not match format %r" %
ValueError: time data 'Geen' does not match format '%d-%m-%Y'