Below is my attempt at constructing a transaction on Fantom

(Keep in mind that Fantom is not EIP-1559 compatible, so the format should be the old one)

contract_txn = contract_SPOOKY_ROUTER.functions.swapExactTokensForTokens(Web3.toWei(1.2, 'ether'), 0, path , address_wallet, block['timestamp']+60 ).buildTransaction({
                                'type': '0x2',
                                'chainId':  250,    # FTM 
                               # 'value' : Web3.toWei(1.5, 'ether'),
                                'gas': 200000,
                                'gasPrice': Web3.toWei('200', 'gwei'),
                                'nonce': nonce,
signed = w3.eth.account.sign_transaction(contract_txn, privatekey)
nonce += 1

When I run this, I end up with the following error message.

    raise TypeError("Unknown kwargs: {0}".format(sorted(unknown_kwargs)))
TypeError: Unknown kwargs: ['gasPrice']

I am having a hard time figuring out where I made a mistake.

1 Answer 1


Type 2 is for EIP-1559 London fork. Use maxFeePerGas and maxPriorityFeePerGas, when using type 2. If the chain doesn't support it, remove type parameter.

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