Why is getTransactionReceipt returning None NoneType object

Question

I am using the following code:

provider = HTTPProvider('http://0.0.0.0:9945')
w3 = Web3(provider)

contract = w3.eth.contract(contract_interface['abi'], bytecode=contract_interface['bin'])

tx_hash = contract.deploy(transaction={'from': w3.eth.coinbase, 'gas': 250000})

print (tx_hash)
time.sleep(1)
tx_receipt = w3.eth.getTransactionReceipt(tx_hash)
print (tx_receipt)
contract_address = tx_receipt['contractAddress']

The tx_hash variable is getting a valid valid but tx_receipt is getting none.

The error I am getting is as follows:
contract_address = tx_receipt['contractAddress']
TypeError: 'NoneType' object is not subscriptable

w3.eth.getTransactionReceipt(tx_hash) function returns None

I dont understand why. Please help.

Answer 1

By looking at your code, it seems like the code "(w3.eth.getTransactionReceipt(tx_hash)" is getting executed before the block has been mined. According to the getTransactionReceipt doc http://web3py.readthedocs.io/en/latest/web3.eth.html#web3.eth.Eth.getTransactionReceipt),
getTransactionReceipt returns None when the transaction has not yet been mined. The sleep(1) is not giving enough time for the
blocks to be mined.

If you are using geth, start mining by turning on --mine or else try while w3.eth.getTransactionReceipt(tx_hash) is None

Answer 2

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Visit: typeerror nonetype object is not subscriptable