Error running on Python3

[Rolf-M]

Hello,
I tried to run the script on an ubuntu linux as well as on a raspbian, but always get the following errors with python3

Traceback (most recent call last):
File "apc-convert.py", line 391, in
apc.load(args.src)
File "apc-convert.py", line 327, in load
for line in filestream:
File "/usr/lib/python3.7/codecs.py", line 322, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xfc in position 70: invalid start byte

Can you help?
Regards, Rolf