web3.py swapExactTokensForTokens事务失败

Question

我正在尝试呼叫路由器合同的swapExactTokensForTokens，我需要将tokenA交换为tokenB。以下是事务的代码：

router = '0x0000000'
abi = '[{"inputs":[{"internalType":"address","name":"_factory","type":"address"},.... {"stateMutability":"payable","type":"receive"}]'

router_contract = w3.eth.contract(router, abi=abi)

tokenA = '0x000...'
tokenB = '0x000...'

path = [tokenA, tokenB]


txn = router_contract.functions.swapExactTokensForTokens(amount, min_amount, path, personal_wallet, (int(time()) +1000) ).buildTransaction({
        'gas': 81000,
        'gasPrice': w3.toWei('10', 'gwei'),
        'nonce':  w3.eth.get_transaction_count(personal_wallet),
    })

我在事务中得到以下错误：

screenshot of the transaction

Answer 1

更新：

当增加gas并在buildTransaction中添加from字段时，上面的代码运行良好。