First let me explain my development environment. I am using Jupyter Notebook to play around with the Web3.py front-end code and Remix for the Solidity smart contract code. I am using the Metamask wallet

firstly i configure the Metamask wallet to pick the Rinkeby network. The i use the Remix IDE to configure it to use Rinkeby, using Injected Web3.

I want to connect to the Rinkeby testnet, using an Infura RPC URL like this;


and i succeed in doing so through the Web3.py code.

when i call a function, which is a call and not a state modifying function, it works fine

e.g the below code works

contract.functions.getMessage().call() # displays a message string

However, whenever i try to make a transaction or call a state modifying function in the contract, say something like

tx_hash = contract.functions.setMessage('Call from Jupyter').transact()

It gives me the following error

The field extraData is 97 bytes, but should be 32. It is quite likely that you are connected to a POA chain.

Refer http://web3py.readthedocs.io/en/stable/middleware.html#geth-style-proof-of-authority for more details.

The full extraData is: HexBytes('0xd883010900846765746888676f312e31322e34856c696e757800000000000000d2c6d883001d158bf0718c1dc64b2809d4c90c9a9450324c22be595e598205e85f5f73d61bd864b3aac4e7ec8f101564cde8faf72cd3ef52b15d3c8a3c6ab6c900')

( I have spaced out the error, into 3 parts, to allow for more legibility )

From what i read in the provided link, i have to use Geth or Parity to successfully conduct transactions on test networks like Rinkeby.

I am also quite confused with the IPC provider mentioned in the above link. I have no idea how to use it ( i think it conflicts with HTTP provider, which is what i intend to use. but feel free to elaborate and clear up any misconceptions on this )

However, if i don't want to use Geth or Parity, is there any method i can use to connect to Rinkeby and conduct transactions by simply using my Infura URL and Web3.py ?

Please let me know any prospective solution or even any relevant work around to this issue

Many thanks

1 Answer 1


Web3 and Metamask are all you need to connect to Rinkeby. You don't need Infura, Geth, or Parity. For state modifying, check out the method send command:

myContract.methods.myMethod([param1[, param2[, ...]]]).send(options[, callback])
  • Well, to be precise, Metamask uses Infura. Commented Feb 20, 2020 at 18:11

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