I made a 250MB json file that should look like this:

[ {"A":"uniquevalue0", "B":[1,2,3]}, 
  {"A":"uniquevalue1", "B":[1]}, 
  {"A":"uniquevalue2", "B":[1,2,3,4]} ]

where the "B" value can be variable len >= 1. This says I have valid JSON.

I call

df = pandas.read_json('ut1.json', orient = 'records', dtype={"A":str, "B":list})

Here is the documentation. When reading into a pandas dataframe, I get the following traceback:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/.../pandas/io/json.py", line 198, in read_json     
    date_unit).parse()
  File "/.../pandas/io/json.py", line 266, in parse 
    self._parse_no_numpy()
  File "/.../pandas/io/json.py", line 496, in _parse_no_numpy
    loads(json, precise_float=self.precise_float), dtype=None)
ValueError: Unexpected character found when decoding 'true'

Can't think of what is going wrong. The python file that is throwing the error is not that helpful.

I had the same error message, and I solved it by using an absolute path.

import os
basePath = os.path.dirname(os.path.abspath(__file__))
df = pandas.read_json(basePath + '/ut1.json', orient = 'records', dtype={"A":str, "B":list})

That worked for me!