UnicodeDecodeError: ‘utf8’ codec can’t decode byte 0xa5 in position 0: invalid start byte

I am using Python-2.6 CGI scripts but found this error in server log while doing json.dumps(),

Traceback (most recent call last):
  File "/etc/mongodb/server/cgi-bin/getstats.py", line 135, in <module>
    print json.dumps(​​__get​data())
  File "/usr/lib/python2.7/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib/python2.7/json/encoder.py", line 201, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python2.7/json/encoder.py", line 264, in iterencode
    return _iterencode(o, 0)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xa5 in position 0: invalid start byte

​Here ,

​__get​data() function returns dictionary {} .

Before posting this question I have referred this of question os SO.

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UPDATES

Following line is hurting JSON encoder,

now = datetime.datetime.now()
now = datetime.datetime.strftime(now, '%Y-%m-%dT%H:%M:%S.%fZ')
print json.dumps({'current_time': now}) # this is the culprit

I got a temporary fix for it

print json.dumps( {'old_time': now.encode('ISO-8859-1').strip() })

But I am not sure is it correct way to do it.

Answer

The error is because there is some non-ascii character in the dictionary and it can’t be encoded/decoded. One simple way to avoid this error is to encode such strings with encode() function as follows (if a is the string with non-ascii character):

a.encode('utf-8').strip()