Bitcoin Forum

Bitcoin => Bitcoin Technical Support => Topic started by: pcmbtc on June 11, 2019, 06:49:52 PM



Title: Help with a transaction. Dropped out of the mempool?
Post by: pcmbtc on June 11, 2019, 06:49:52 PM
Hello everyone,

I’ve been having trouble with a transaction I made yesterday. I set a 1sat/b fee, since I’m not at all in a hurry to have it confirmed. I woke up today and went to check and it is no longer anywhere to be found on a block explorer. The transaction doesn’t exist on any explorer and, naturally, the original output hasn’t been spent and the destination address hasn’t received anything either.

I imagine this means it dropped out of the mempool? This has never happened to me before and I’m not quite sure how it works. It had only been about 12 hours since I had made it. I thought it usually spent a lot longer in there before it dropped.

Anyway, here is where the problem starts: I’ve made the transaction using a Ledger Nano S. According to Ledger Live, the desktop software,  the transaction still exists, though it has no confirmations. There is a sync button in there that supposedly updates the info from the blockchain, but nothing happens when I press it. In the ledger support website, they suggest I clear the software’s cache which would allow it to solve any syncing issues but no luck. I’ve even reset all accounts from Ledger Live and paired the device again and still, nothing.

So, what now? I thought about doing a RBF but I suppose Ledger would try to spend it from the change address of the original transaction, which hasn’t been confirmed. There were no other outputs in the wallet. What happens then?

Would a Child-Pays-For-Parent work for this?

Thanks in advance, any help is appreciated!


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: TryNinja on June 11, 2019, 06:56:45 PM
I’ve been having trouble with a transaction I made yesterday. I set a 1sat/b fee, since I’m not at all in a hurry to have it confirmed. I woke up today and went to check and it is no longer anywhere to be found on a block explorer. The transaction doesn’t exist on any explorer and, naturally, the original output hasn’t been spent and the destination address hasn’t received anything either.

I imagine this means it dropped out of the mempool? This has never happened to me before and I’m not quite sure how it works. It had only been about 12 hours since I had made it. I thought it usually spent a lot longer in there before it dropped.
Are you sure you're searching for the right transaction? (is the tx id right? which block explorer are you using?)
Transactions don't get dropped after only 12 hours. I've had a few that lasted days before getting confirmed.

Anyway, here is where the problem starts: I’ve made the transaction using a Ledger Nano S. According to Ledger Live, the desktop software,  the transaction still exists, though it has no confirmations. There is a sync button in there that supposedly updates the info from the blockchain, but nothing happens when I press it. In the ledger support website, they suggest I clear the software’s cache which would allow it to solve any syncing issues but no luck. I’ve even reset all accounts from Ledger Live and paired the device again and still, nothing.
Try using your Nano S with the Electrum wallet. How to: https://support.ledger.com/hc/en-us/articles/115005161925-Set-up-and-use-Electrum

See if the transaction shows up there. If it does, right click -> Details -> Copy; then, go to a few tx broadcasters [1] (https://www.blockchain.com/btc/pushtx) [2] (https://live.blockcypher.com/btc/pushtx/) [3] (https://blockchair.com/broadcast), paste the code there and submit it.

So, what now? I thought about doing a RBF but I suppose Ledger would try to spend it from the change address of the original transaction, which hasn’t been confirmed. There were no other outputs in the wallet. What happens then?

Would a Child-Pays-For-Parent work for this?
It would to get it confirmed quickly. Just open your Nano S wallet with Electrum and follow these instructions: https://bitcoinelectrum.com/how-to-do-a-manual-child-pays-for-parent-transaction/


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: seoincorporation on June 11, 2019, 07:01:09 PM
The best way to avoid this happen is to use the right fees, and to estimate them you could use these two tools:

https://www.blockchain.com/es/btc/unconfirmed-transactions
https://bitcoinfees.earn.com/


The first one shows the unconfirmed transactions, and the second one is the fees recommendation for your transaction if you use 88 satoshis/byte your transaction should confirm in the next block.

And i get your point, your transaction shouldn't be dropped from the pool... should only take a long time to confirm, not sure why it gets dropped, i should look to the txid to verify what was the problem.


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: o_e_l_e_o on June 11, 2019, 07:21:52 PM
Are you sure your fee was above 1 sat/vByte? Bitcoin Core defaults the minimum relay fee (https://bitcoin.org/en/glossary/minimum-relay-fee) to 1 sat/vByte. Although users are free to change this, most do not. If your fee was below this, then it won't propagate through the network and so won't be found on block explorers and won't be confirmed. Follow the instructions from TryNinja regarding Electrum and CPFP.

https://bitcoinfees.earn.com/
This site always grossly overestimates the fees required unless you are absolutely desperate to get in to the next block. Otherwise, a much better estimation can be taken from here: https://www.coinb.in/#fees


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: pcmbtc on June 11, 2019, 08:20:04 PM
Ok, it seems to be an issue with the block explorers. Both Blockstream and Blockcypher were showing the transaction last night but not today, which led me to believe it had been dropped from the mempool. Now I've found it on blockchainDOTcom's explorer. Still no confirmations, which is fine. I know different explorers can have conflicting info based on different mempools but i didnt realise it could disappear once it was there.

Odd thing is that if i keep refreshing the tx page on blockstream's explorer, it will sometimes find the tx and sometimes won't.

Well, anyways. Guess now I just have to wait for the confirmations

Thx for the help guys, much appreciated.


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: nc50lc on June 12, 2019, 03:42:35 AM
Odd thing is that if i keep refreshing the tx page on blockstream's explorer, it will sometimes find the tx and sometimes won't.
Try to broadcast it using their own broadcaster (nodes) to manually include your TX to their nodes.
This wont help you get confirmation but it may keep that TX included to their nodes.

Blockstream Broadcast TX (https://blockstream.info/tx/push) | Blockcypher Broadcast TX (https://live.blockcypher.com/btc/pushtx/)

<!> There seems to be a problem with blockcypher's server.


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: joniboini on June 12, 2019, 03:49:49 AM
I had the same problem as you in the past. Not sure what the reason is, but I think that blockchain explorer has some kind of different data or algorithm. My transaction is shown in one explorer but not the other, it's around 2 MB from the tip, so I assume the other explorer only shows up to below that point, or consider transactions below that point as dropped.

I did RBF that time, increase the fee a little bit and luckily it gets confirmed sooner than I expected.


Title: Re: Help with a transaction. Dropped out of the mempool?
Post by: o_e_l_e_o on June 12, 2019, 10:38:12 AM
Different block explorers pull their data from different nodes. If your transaction has a low fee, has been very recently broadcast, the mempool is very congested, or other things along those lines, then your transaction may be present in some nodes and not others, and therefore show up on some block explorers and not others.

The issue with it showing up on a block explorer, then disappearing, then reappearing, is a slightly more unusual one. It could be that the block explorer in question is pulling data from a number of nodes, and you run in the scenario I have described above. Or it could be your transaction was dropped from a node for whatever reason, and then later picked up again.