Just started looking at Web3 and I'm currently trying to listen for an event emitted by a smart contract on the Polygon network by using

event_filter = contract.events.<MyEvent>.createFilter(fromBlock='latest')

I've tried three different providers, Infura (https), maticvigil and Alchemy (both https and wss), but when calling the method createFilter I get the response

{'code': -32601, 'message': 'Unsupported method: eth_newFilter.'}

When using the method in the Ethereum mainnet everything goes smoothly, but as soon as I change to a Polygon provider I get a similar error for all providers.

If I understand what's happening, that means that in order for me to listen to an event using that Web3 method the provider has to implement eth_newFilter

So my question is, does anyone happen to know of a provider for the Polygon network that implements the eth_newFilter method on their API?

Alternatively I would appreciate some guidance/sources on how to listen for a particular event triggered by a smart contract on the Polygon network without having to rely on a provider, thanks.

1 Answer 1


For future readers, apparently Polygon does not support eth_newFilter so a way to get events thru Web3 is subscribing to logs (currently available thru Web3.js) or using get_logs (if u wanna do it in python), I found an example in a reddit post, goes like this:

from web3 import Web3
from web3._utils.events import get_event_data

w3 = Web3(Web3.HTTPProvider("<Infura host>"))
contract = w3.eth.contract(address="0x33..", abi=abi['abi'])
event_template = contract.events.<EVENT_NAME>
events = w3.eth.get_logs({'fromBlock':from_block, 'toBlock': from_block+10000, 'address':"0x33.."})

def handle_event(event, event_template):
        result = get_event_data(event_template.web3.codec, event_template._get_event_abi(), event)
        return True, result
        return False, None

for event in events: 
    suc, res = self.handle_event(event=event, event_template=event_template)   
    if suc:
        print("Event found", res)
  • This totally worked! Waiting for the WS version once Infura decide to publish it.
    – max246
    Feb 20, 2022 at 11:45

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