ValueError: {'code': -32000, 'message': 'invalid sender'} when calling transferFrom using web3.py

Question

I want to make a function that allows you to send tokens from one owner to another.

    nonce = w3.eth.getTransactionCount(from_['address'])

    unsigned_transaction = contract.functions.transferFrom(
        from['address'],
        to['address'],
        1
    ).buildTransaction({
        'chainId': 1,
        'gas': 70000,
        'gasPrice': w3.toWei('1', 'gwei'),
        'nonce': nonce,
    })

    signed_transaction = sign_transaction(
        unsigned_transaction,
        from['private']
    )

    tx_ref = send_transaction(signed_transaction)

But I get the following error:

ValueError: {'code': -32000, 'message': 'invalid sender'}

What am I doing wrong?

Who in this case is the sender? What's wrong with him?

Answer 1

It's 'chainId' problem. mainnet is 1, ropsten is 3

Answer 2

This error message is directly from Ethereum node, not web3.py:

ValueError: {'code': -32000, 'message': 'invalid sender'}

My gut feeling is that from['address'] account is not configured on your Ethereum node - private key not imported. Thus, your Ethereum node cannot sign the transaction and send it.