TypeError: object of type 'NoneType' has no len()

[letmejustputthishere]

When I run this code

from ic.client import Client
from ic.identity import Identity
from ic.agent import Agent
from ic.candid import encode, Types
import time
import schedule
import sys

# params is an array, return value is encoded bytes
# params = [{'type': Types.Nat, 'value': 10}]
# data = encode(params)

# Identity and Client are dependencies of Agent
iden = Identity()  # creates a random keypair
client = Client()  # creates a client to talk to the IC
# creates an agent, combination of client and identity
agent = Agent(iden, client)

def main():
    backup(canister_id=sys.argv[1])
    schedule.every(5).seconds.do(backup, canister_id=sys.argv[1])

    while True:
        schedule.run_pending()
        time.sleep(1)

def backup(canister_id):
    print(f"disburse completed at {time.ctime()}")
    # query the NFT canister
    # doesnt change after calling `shuffleAssets`
    result = agent.update_raw(
        canister_id, "disburse", encode([]))

    print(result) 

get the following error after a couple of iterations:

Traceback (most recent call last):
  File "/home/moritz/.venv/bin/backup", line 8, in <module>
    sys.exit(main())
  File "/home/moritz/.venv/lib/python3.8/site-packages/state_backup/backup.py", line 25, in main
    schedule.run_pending()
  File "/home/moritz/.venv/lib/python3.8/site-packages/schedule/__init__.py", line 780, in run_pending
    default_scheduler.run_pending()
  File "/home/moritz/.venv/lib/python3.8/site-packages/schedule/__init__.py", line 100, in run_pending
    self._run_job(job)
  File "/home/moritz/.venv/lib/python3.8/site-packages/schedule/__init__.py", line 172, in _run_job
    ret = job.run()
  File "/home/moritz/.venv/lib/python3.8/site-packages/schedule/__init__.py", line 661, in run
    ret = self.job_func()
  File "/home/moritz/.venv/lib/python3.8/site-packages/state_backup/backup.py", line 33, in backup
    result = agent.update_raw(
  File "/home/moritz/.venv/lib/python3.8/site-packages/ic/agent.py", line 92, in update_raw
    return decode(result)
  File "/home/moritz/.venv/lib/python3.8/site-packages/ic/candid.py", line 1123, in decode
    b = Pipe(data)
  File "/home/moritz/.venv/lib/python3.8/site-packages/ic/candid.py", line 45, in __init__
    self._view = buffer[0:len(buffer)]
TypeError: object of type 'NoneType' has no len()

[letmejustputthishere]

Maybe this is related to this? https://forum.dfinity.org/t/calling-a-counter-multiple-times-asynchronously-with-promise-all-gives-the-same-value-each-time/11618/

[Myse1f]

What's ur canister id? Then I could have a try,

[letmejustputthishere]

djkni-kiaaa-aaaae-qabua-cai

I tried to use different cron mechanisms, but all of them lead to the same error. Seems like calling the same update_raw in a small timeframe leads to this error.

[letmejustputthishere]

this also appears:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/moritz/ethflower-disburse/off-chain-backup/state_backup/backup.py", line 38, in main
    s.run()
  File "/home/moritz/.pyenv/versions/3.8.6/lib/python3.8/sched.py", line 151, in run
    action(*argument, **kwargs)
  File "/home/moritz/ethflower-disburse/off-chain-backup/state_backup/backup.py", line 27, in backup
    result = agent.update_raw(
  File "/home/moritz/ethflower-disburse/.venv/lib/python3.8/site-packages/ic/agent.py", line 91, in update_raw
    result = self.poll(canister_id, req_id)
  File "/home/moritz/ethflower-disburse/.venv/lib/python3.8/site-packages/ic/agent.py", line 121, in poll
    status, cert = self.request_status_raw(canister_id, req_id)
  File "/home/moritz/ethflower-disburse/.venv/lib/python3.8/site-packages/ic/agent.py", line 111, in request_status_raw
    cert = self.read_state_raw(canister_id, paths)
  File "/home/moritz/ethflower-disburse/.venv/lib/python3.8/site-packages/ic/agent.py", line 103, in read_state_raw
    d = cbor2.loads(ret)
_cbor2.CBORDecodeValueError: unknown unsigned integer subtype 0x1c

[Myse1f]

I ran ur code about serveral minutes, but no error occured. Can you find a specific method to reproduce the issue?

Besides, what's ur current version of ic-py.

[letmejustputthishere]

i updated to 1.0.0, thanks for the hint! i will keep an eye on it and see whether the error pops up again

[letmejustputthishere]

still happens :/

did you make sure you ran the code in the loop? i think repeatedly calling update_raw within a couple of seconds causes the issue

[Myse1f]

yes, I ran the code you provide.

[letmejustputthishere]

i'm running the code in this branch using python 3.8.6 on ubuntu 20.04 https://github.com/flowerpowerdao/off-chain-backup/tree/disburse

[letmejustputthishere]

you need to remove the except: pass to see the errors

[Myse1f]

Can you paste your error message here with new version?

[letmejustputthishere]

my bad, i didnt update the dependencies on my server! it works now and yields None instead of the errors from before. Why does that happen? Is the call failing or the IC not answering?

[Myse1f]

I think it’s timeout for waiting the result. Update call is asynchronous and we keep querying the result for 10s. If timeout, it returns None.

Maybe we can expose the argument for setting the timeout.

[letmejustputthishere]

With dfx I think i never had a timeout, why does it happen so frequently with ic-py?

[letmejustputthishere]

Maybe we can expose the argument for setting the timeout.

That would be cool

[Myse1f]

43

1. update_raw timeout default to infinite
2. update_raw(..., timeout=) to set the polling timeout