Facing the exact same issue on the import of either the Lexer or Parser generated from the JSON and Protobuf3 grammars from the antlr/gramars-v4 repo https://github.com/antlr/grammars-v4/tree/master/

[philipmiesbauer]

          Facing the exact same issue on the import of either the Lexer or Parser generated from the JSON and Protobuf3 grammars from the antlr/gramars-v4 repo https://github.com/antlr/grammars-v4/tree/master/

Traceback (most recent call last):
  File "/home/<user>/gitRepos/loki-external-interfaces/parse_json.py", line 3, in <module>
    from grammars import Protobuf3Parser
  File "/home/<user>/gitRepos/loki-external-interfaces/grammars/Protobuf3Parser.py", line 194, in <module>
    class Protobuf3Parser ( Parser ):
  File "/home/<user>/gitRepos/loki-external-interfaces/grammars/Protobuf3Parser.py", line 198, in Protobuf3Parser
    atn = ATNDeserializer().deserialize(serializedATN())
  File "/home/<user>/.local/lib/python3.10/site-packages/antlr4/atn/ATNDeserializer.py", line 61, in deserialize
    self.reset(data)
  File "/home/<user>/.local/lib/python3.10/site-packages/antlr4/atn/ATNDeserializer.py", line 91, in reset
    temp = [ adjust(c) for c in data ]
  File "/home/<user>/.local/lib/python3.10/site-packages/antlr4/atn/ATNDeserializer.py", line 91, in <listcomp>
    temp = [ adjust(c) for c in data ]
  File "/home/<user>/.local/lib/python3.10/site-packages/antlr4/atn/ATNDeserializer.py", line 89, in adjust
    v = ord(c)
TypeError: ord() expected string of length 1, but int found

The parse_json.py file uses only a custom version of the offical antlr documetnio demo for python3

import sys
from antlr4 import *
from grammars import Protobuf3Parser
from grammars import Protobuf3Lexer

def main(argv):
    input_stream = FileStream(argv[1])
    lexer = Protobuf3Lexer(input_stream)
    stream = CommonTokenStream(lexer)
    parser = Protobuf3Parser(stream)
    tree = parser.startRule()

if __name__ == '__main__':
    main(sys.argv)

Originally posted by @philipmiesbauer in https://github.com/antlr/antlr4/issues/4213#issuecomment-1567091592

[philipmiesbauer]

The Lexer and Parser were generated with the command

antlr4 -Dlanguage=Python3 grammars/*.g4

with antlr4 version 4.13.0

[philipmiesbauer]

Fault was on my side.

My imports should have been

import sys
from antlr4 import *
from grammars.Protobuf3Parser import Protobuf3Parser
from grammars.Protobuf3Lexer import Protobuf3Lexer

def main(argv):
    input_stream = FileStream(argv[1])
    lexer = Protobuf3Lexer(input_stream)
    stream = CommonTokenStream(lexer)
    parser = Protobuf3Parser(stream)
    tree = parser.startRule()

if __name__ == '__main__':
    main(sys.argv)