null is returned when getting pending transaction

[gotsteez]

I am using Infura as the provider for monitoring pending transactions, and came across this hash: 0x8dc4bac12a7961aa794f51bc9bf2b09362515ac62b88413bc45e78aa06adc61d. If I try to do await provider.eth.getTransaction(hash), it returns null, but on etherscan it exists (here)[https://etherscan.io/tx/0x8dc4bac12a7961aa794f51bc9bf2b09362515ac62b88413bc45e78aa06adc61d]. Is this a bug, or am I doing something wrong?

[zemse]

The provider.eth.getTransaction call simply does the eth_gettransactionbyhash rpc call under the hood. If the backend node (server at provider URL) has the transaction in it's mempool it will return it else it will just return null, which ethers will pass to you.

When someone submits a signed transaction to the ethereum network, it takes some time to be propagated around, so it is possible to see a tx on Etherscan while not on your node (and vice versa). You can specifically use the Etherscan provider for this purpose, or you can add logic to retry fetching the tx after few secs from Infura.

Edit: I noticed the tx hash you provided has a pending tx with lower nonce. Though I am not sure but it is possible for Infura's node to not import such a tx in their mempool.