I sent a transaction with far too low fee and it's stuck in mempool.

I'm trying to do a double-spend with a higher fee without any luck.

My wallet: 15Zz2KP5iA7oVarmtmBvb9ZHUmQaSFL9M8

Unconfirmed transaction: 0b0177688485922027b336c24e765fdea8dc03d2ad79f87019705f2ca9fb970a

I'm using coinb.in to create, sign and broadcast transaction but I get Error: 64: scriptsig-not-pushonly.

The transaction seems to be valid when I verify it.

Can anyone point my in the right direction for this?

  • I've added an answer to the specific problem, however, I do not recommend to try to double spend the transaction, since I don't think it will work. If first transaction is already in most of the nodes mempool, the new one will be treated as a double spend and be rejected. The best you can do is either wait, or create a transaction spending from you first one (the one with low fees) and adding a higher fee that new transaction (using what is called Child pays for Parent). – sr-gi Mar 14 '17 at 17:05

You are building an incorrect scriptSig.

Notice that, if you check the scriptSig of every input from the transaction you provided, it looks like:


Which has the following structure:


However, this is not what is expected to be found in a scriptSig, but what will be expected in the scriptPubKey field.

What you have to do is provide the correct script in the scriptSig field of each input of the transaction, that would correspond to the signature of the transaction if you are creating a P2PKH transaction, or the script that matches with the script-hash from the UTXO you are spending, in case you are building a P2SH transaction.

  • I did wonder where the answer went :) . Thanks for the answer. Do you have any suggestions of site's that might be able do make this process easier? coinb.in doesn't seem to have the options I need. – James Jackson Mar 14 '17 at 17:15
  • I messed up a little with the first answer, since the scripts where like switched and something does not seems right. I preferred to refrase it :P. What are you trying to do? – sr-gi Mar 14 '17 at 17:20
  • I mean, what do you mean with "this process"? – sr-gi Mar 14 '17 at 17:48
  • The process of creating the correct transaction. I was using coinb.in because it seemed like it would simplify the process but it's "transaction" generator doesn't seem to do what it needs to do to correctly make this transaction. – James Jackson Mar 15 '17 at 16:30
  • Well, if you need to create a transaction you will need to manage the keys associated with the Bitcoin addresses where the bitcoins are "stored". In order to sign the transactions in P2PKH transactions or to create the proper scripts in P2SH. What I think is that when you used the coinb.in tools, you forgot to sign the transaction (I'm not used to the tool, so I can be wrong). In conclusion, you will need something more similar to a wallet. – sr-gi Mar 15 '17 at 21:22

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