Function 'sendTransaction' - can any error occur before the 'transactionHash' event?

Question

Function web3.eth.sendTransaction can throw an error.

For example:

• Transaction gas is too low
• Transaction execution error

But can it possibly throw an error before emitting the transactionHash event?

I am pretty sure that the two errors above cannot possibly occur at this point.

Am I right?

What about other errors?

For example, what if there's a network problem, or an Ethereum-client problem?

Here is a coding example (taken directly from the docs), with the question embedded:

web3.eth.sendTransaction({
    from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
    to: '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe',
    value: '1000000000000000'
})
.on('transactionHash', function(hash){
    // Can it possibly throw an error before reaching here?
})
.on('receipt', function(receipt){
    ...
})
.on('confirmation', function(confirmationNumber, receipt){ ... })
.on('error', console.error); // If a out of gas error, the second parameter is the receipt.

Thank you!

Answer 1

Yes ofcourse, a lot of errors can occur before emitting of transactionHash event. Example being:

• basic validations like invalid sender address, receiver address, amount , gas etc.
• When amount one is trying to send is more than his balance

So basically there is a number of validations by the client before sending a transaction to the blockchain and failure of any such validaion will result into a failure of tx even before getting hash.

I read somewhere list of validations that happen before sending of tx. I'll try to fetch that. So all those cases may cause failure even before getting hash.