> error in score.py?

Sometimes the following error occurs in score.py:

Traceback (most recent call last):
File "/tmp/codalab/tmp50prp7/run/program/score.py", line 319, in
main()
File "/tmp/codalab/tmp50prp7/run/program/score.py", line 311, in main
ingestion_info = _get_ingestion_info(args)
File "/tmp/codalab/tmp50prp7/run/program/score.py", line 290, in _get_ingestion_info
ingestion_info = json.load(ftmp)
File "/usr/lib/python3.6/json/__init__.py", line 299, in load
parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
File "/usr/lib/python3.6/json/__init__.py", line 354, in loads
return _default_decoder.decode(s)
File "/usr/lib/python3.6/json/decoder.py", line 339, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/lib/python3.6/json/decoder.py", line 357, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

I have checked the ingestion log and confirmed that the prediction has been generated within the time budget. And it seems that sometimes this error will vanish if I rerun the same code again. Does anyone know the reason of this error? Thanks~