NotImplementedError: Decoder class for "Compact<u32>" not found

[sergpsu]

Hi The exception occurs from time to time in different scenarios but always for Compact<u32> type. Have to mention that few instances of py-substrate-interface is used in parallel in different async tasks. Also it seems that the exception occurs only at the start, so if it does not happen at once then it should not happen ever. We are using py-substrate-interface 1.3.0, scalecodec 1.0.42 and python 3.8 Here are two logs

1. Block subscription

2022-09-21 18:52:01,654 [ERROR] Future exception was never retrieved
future: <Future finished exception=NotImplementedError('Decoder class for "Compact<u32>" not found')>
Traceback (most recent call last):
  File "/usr/lib/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/app/./ps.py", line 480, in wait_block_finalized
    substrate.isubstrate.subscribe_block_headers( subscription_handler_f, finalized_only=True )
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 2810, in subscribe_block_headers
    return self.__get_block_handler(
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 2563, in __get_block_handler
    self.init_runtime(block_hash=block_hash)
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 1136, in init_runtime
    self.metadata_decoder = self.get_block_metadata(block_hash=runtime_block_hash, decode=True)
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 940, in get_block_metadata
    metadata_decoder.decode()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 552, in process
    member_obj = self.process_type(member_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 1896, in process
    value = super().process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 1064, in process
    result_obj = self.process_type(enum_type_mapping[1], metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 135, in process
    self.value_object = self.process_type(self.sub_type)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 159, in process
    length = self.process_type('Compact<u32>').value
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 759, in process_type
    obj = self.runtime_config.create_scale_object(type_string, self.data, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 168, in create_scale_object
    raise NotImplementedError('Decoder class for "{}" not found'.format(type_string))
NotImplementedError: Decoder class for "Compact<u32>" not found

2. substrate_interface.query() call

future: <Task finished name='IPFS BOOTSTRAP' coro=<ParameterServer.ipfs_bootstrap() done, defined at /app/./ps.py:904> exception=NotImplementedError('Decoder class for "Compact<u32>" not found')>
Traceback (most recent call last):
  File "/app/./ps.py", line 915, in ipfs_bootstrap
    if not self.substrate.get_vendor(VENDOR_NAME):
  File "/app/./lib/py_substrate/substrate.py", line 857, in get_vendor
    res = self.isubstrate.query(
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 1361, in query
    self.init_runtime(block_hash=block_hash)
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 1136, in init_runtime
    self.metadata_decoder = self.get_block_metadata(block_hash=runtime_block_hash, decode=True)
  File "/usr/local/lib/python3.8/dist-packages/substrateinterface/base.py", line 940, in get_block_metadata
    metadata_decoder.decode()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 552, in process
    member_obj = self.process_type(member_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 1896, in process
    value = super().process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 1064, in process
    result_obj = self.process_type(enum_type_mapping[1], metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 1064, in process
    result_obj = self.process_type(enum_type_mapping[1], metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 830, in process
    element = self.process_type(self.sub_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 506, in process
    field_obj = self.process_type(data_type, metadata=self.metadata)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 135, in process
    self.value_object = self.process_type(self.sub_type)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 760, in process_type
    obj.decode(check_remaining=False)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 677, in decode
    self.value_serialized = self.process()
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/types.py", line 159, in process
    length = self.process_type('Compact<u32>').value
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 759, in process_type
    obj = self.runtime_config.create_scale_object(type_string, self.data, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/scalecodec/base.py", line 168, in create_scale_object
    raise NotImplementedError('Decoder class for "{}" not found'.format(type_string))
NotImplementedError: Decoder class for "Compact<u32>" not found

[zhoujs93]

Hi, has there been any issue around ? Currently running into the same problem