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50 votes
Accepted

How do transactions leave the memory pool?

As of Bitcoin Core 0.14.0, these are the ways a transaction can leave the mempool: The transaction was included in a block. The transaction or one of its unconfirmed ancestors conflicts with a ...
Pieter Wuille's user avatar
27 votes

Why is my transaction not getting confirmed and what can I do about it?

Here is a guide for as many wallets as I could figure out how to perform an RBF with. This is adapted from my bitcointalk post: https://bitcointalk.org/index.php?topic=1802212.0 What is a "Stuck" ...
Ava Chow's user avatar
  • 70.5k
25 votes

Why is my transaction not getting confirmed and what can I do about it?

In the case that your fee is too low: Now that child-pays-for-parent has been merged, you(or any of the recipients of your unconfirmed transaction) could spend the Bitcoin received and the fee ...
Steve Ellis's user avatar
  • 1,072
16 votes
Accepted

So I mined a block, but why would other nodes accept my mined block?

The incentive to mine on the currently longest chain is that there is a risk to the dishonest miner that honest, non-mining nodes may have already propagated the first block and hence reject and not ...
Matthew Stannard's user avatar
16 votes

What is meant by transaction 'pinning'?

Transaction pinning happens when: I broadcast a transaction that signals opt-in RBF the transaction does not get confirmed because the feerate is too low someone else broadcasts a new (child) ...
jnewbery's user avatar
  • 1,060
15 votes

Replace-by-Fee vs Child-pays-for-Parent?

Replace-by-fee means transactions spending the same coin to the same addresses are not considered double-spends by the network and are still relayed, as long as they pay a higher fee than the ...
maservant's user avatar
  • 1,031
13 votes

Why is my transaction not getting confirmed and what can I do about it?

The other answers cover most useful information already, I'd like to add one point though: The fee estimation of most wallets has significantly improved since blocks have gotten full. If you're ...
Murch's user avatar
  • 75.5k
11 votes
Accepted

Why doesn't the protocol allow unconfirmed transactions to expire at a given height?

This question was answered by Satoshi. My attempt to paraphrase: Suppose a transaction T specified an expiration height, X, and was mined in block X. Then its outputs were spent, possibly many times ...
Larry Ruane's user avatar
9 votes
Accepted

What does "lock time" mean?

A specified locktime indicates that the transaction is only valid after a given blockheight. Since the locktime field indicated is 419382 and currently the latest blockheight as of 12th July 2016 1108 ...
rny's user avatar
  • 2,418
9 votes
Accepted

Are Micropayment channels still subject to malleability after BIP65?

There are a variety of different ways to construct a micropayment channel, but there are two designs that I think are particularly relevant to your question about "simple, one-directional, ...
David A. Harding's user avatar
9 votes

What (if anything) in the bitcoin protocol prevents bias against certain accounts?

The solution to this problem is: anyone can become a miner, in theory. Proof of work replaces a central party that can censor with a consensus protocol, where miners jointly decide what transactions ...
Pieter Wuille's user avatar
8 votes

Why is my transaction not getting confirmed and what can I do about it?

If you are using Electrum, there is no equivalent to -zapwallettxes. The closest thing you can do is to restore your wallet from a seed. This will wipe your client of any unconfirmed transactions. ...
Nick ODell's user avatar
  • 29.4k
8 votes

Do unconfirmed transactions expire after some time?

In addition to Mark S.'s answer, since Bitcoin Core 0.12 there actually is an expiration in the mempool, which evicts unconfirmed transactions after N hours, where N is set by -mempoolexpiry, and ...
Pieter Wuille's user avatar
8 votes

How do you apply "-zapwallettxes" on Windows?

-zapwallettxes removes all wallet transactions that are not in the blockchain. It can remove "stuck" transactions, although you don't need this feature in normal operations mode. Solution A) On ...
Jonas Schnelli's user avatar
8 votes
Accepted

How to unstuck a low-fee transaction with Electrum?

I've just visited #electrum on IRC to get some advice. While restoring from a seed may make your wallet forget a transaction and allow you to resend it with a higher fee, abpa there told me that this ...
Murch's user avatar
  • 75.5k
8 votes
Accepted

Can RBF be used to change the value of a transaction?

However, is it possible to use RBF to change the value of the transaction or zero value (in case of cancellation)? Yes, there is no restriction on transactions only changing the fee. In fact, that's ...
Pieter Wuille's user avatar
7 votes

How do transactions leave the memory pool?

There is no fixed expiration time for each node, but the default setting is 72 hours. https://bitcoin.stackexchange.com/a/43165/24926
inersha's user avatar
  • 3,083
7 votes
Accepted

Requirements to accept and send SegWit transactions?

How does that work, do they look like normal addresses? Will older non-SegWit clients also be able to send txs to such addresses? Or is it a new address format, that will not be recognized by older ...
Ava Chow's user avatar
  • 70.5k
6 votes

How can an unconfirmed transaction be removed from the memory pool?

Try the removeprunedfunds RPC command. It deletes the specified transaction from the wallet. … This will effect wallet balances.
Geremia's user avatar
  • 4,636
6 votes
Accepted

What is the largest number of blocks a transaction has ever waited for confirmation?

This is not a full answer, but a partial answer somebody may use as a stepping stone to craft a complete answer. E.g. blockchain.info shows both "received time" and the time of the block a ...
Murch's user avatar
  • 75.5k
6 votes
Accepted

Spending output of a low-fee transaction by following with higher-fee transaction

There are 3 cases. Case 1a: if Fee(Tx1) < Dust Fee then Tx1 gets dropped by nodes that do not offer Free Relay Policy. Then all other transaction dependent on the outputs of Tx1 will never be ...
rny's user avatar
  • 2,418
6 votes
Accepted

How did these zero-transaction fee transactions make it into the Bitcoin network?

Zero- and low-fee transactions aren't relayed by default. If you attempt to broadcast one over the Bitcoin peer-to-peer network, most nodes won't pass it along for you (and they might even "ban" you ...
Nate Eldredge's user avatar
6 votes

Where are transactions to be confirmed stored?

Full nodes keep a "mempool" of unconfirmed transactions, so yes, but every full node chooses its own rules for how many transactions it keeps in the mempool, e.g. minimum fee, maximum number of ...
meshcollider's user avatar
  • 11.8k
6 votes
Accepted

Transaction with highest fee, but stuck, what did I do wrong?

The hourly average fee when this question was posted was between 9 and 10 Satoshi per Byte (sat/B). The latest TX's that I just randomly checked all had 10.03 sat/B fee which is higher than the 4.5 ...
Jose Fonseca's user avatar
6 votes

Longest unconfirmed transaction?

A transaction could go unconfirmed indefinitely. The order in which transactions are confirmed is decided by miners, and generally they will be incentivized to include only the highest fee-rate ...
chytrik's user avatar
  • 18.3k
6 votes

Can an unconfirmed transaction be confirmed several years later?

Yes, that is possible. If the UTXOs still exist and the transaction is otherwise valid, then it could still be confirmed after all of that time.
chytrik's user avatar
  • 18.3k
5 votes
Accepted

Do transactions with old UTXOs take longer to confirm?

No. The miners use Bitcoin Core or similar full node software to determine which transactions are valid and suitable for inclusion in a block. Bitcoin Core maintains a database of all unspent UXTOs. ...
Nate Eldredge's user avatar
5 votes
Accepted

Is 8 the maximum number of incoming peer connections?

The reference here for running the bitcoin daemon does not really clarify what maxconnections mean. Furthermore, that maxconnections only controls the number of inbound connections and not outbound. ...
Nick ODell's user avatar
  • 29.4k
5 votes
Accepted

Replaceable transaction or Non-replaceable. How can I identify it from raw transaction?

From BIP-125 Opt-in Full Replace-by-Fee Signaling: This policy specifies two ways a transaction can signal that it is replaceable. Explicit signaling: A transaction is considered to have ...
sr_gi's user avatar
  • 3,220

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