120 votes

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

How Bitcoin Mining Works Bitcoin transactions are mined (processed) by Miners, and Miners want to benefit from their work. By mining transactions with higher fees, they make more money. Some miners ...
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  • 1,453
38 votes
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Can bitcoin exist without miners?

if in the coming years the difficulty increases so much that mining is no longer profitable That's not really possible. The mining power is set so that the miners need 10 minutes in average to mine a ...
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  • 2,047
31 votes

Bitcoin successfully deducted on sender wallet but did not reach receiver wallet

It's not completely clear what the situation is, but from what I gather it seems that you're the sender and the recipient is not acknowledging a payment you have sent. I assume that you have verified ...
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  • 63.4k
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 ...
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  • 1,034
24 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" ...
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  • 61.4k
15 votes
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With 100% segwit transactions, what would be the max number of transaction confirmation possible on a block?

Very interesting question, let's see what the smallest transaction we can build is. For it to be minimal it has to be a single input and a single output. The non-segwit part would look something like ...
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  • 8,754
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 ...
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  • 63.4k
12 votes
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When to worry about 1-confirmation payments

The thing to consider is, "what does the attacker have to give up in order to attack me?" If the cost of that thing is less than the reward from a successful attack, then attacking is rational from a ...
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12 votes
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Shortest and Longest block interval time ever recorded in Bitcoin

(This data is current through block 535276.) Based on block timestamps (which do not have to be accurate), the longest difference between successive blocks is 463160 seconds (5 days, 8 hours, 39 ...
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10 votes
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How does BitCoin prevent fraud during confirmation period?

This is definitely a concern, and is the reason why Bitcoin users are encouraged to wait for several confirmations before accepting a transaction and delivering goods. It's not quite as easy as you ...
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9 votes
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If you confirm others' transactions, what do you do to earn 25 bitcoins per block?

Just to give some specifics in addition to David Grayson's answer: At current difficulty levels, mining a block requires computing an average of 29,973,900,941,385,007,104 hash operations. An ...
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9 votes

What is the "confirmation" field in a block?

Blocks in Bitcoin, as they exist in the blockchain, don't actually contain a confirmation field. When you query for a block in bitcoin-rpc or similar, additional information is added to the block ...
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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. ...
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8 votes

If you confirm others' transactions, what do you do to earn 25 bitcoins per block?

It is a lot of work and it requires a lot of computing power. To get the 25 BTC reward for a block (also known as the coinbase reward), you have to create the block in the first place. It is ...
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7 votes

Bitcoind -walletnotify more than 6 confirmations?

The Bitcoin Core -walletnotify should only run at most twice for a typical transaction: When the transaction enters the local node's mempool When a block arrives containing that transaction. I haven'...
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7 votes
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Can you mine without transactions?

This is essentially correct: the protocol leaves it up to the miner to decide which transactions to include in a block. There is no requirement for them to include any transactions at all, other ...
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7 votes
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When we can agree on mempool sorting order, we can just confirm first n-transactions that are at least 10 mins old. What's missing?

Your answer assumes different nodes can have a consistent view of the mempool. If that were the case, we wouldn't need a blockchain at all, whose sole purpose is establishing consistency between ...
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6 votes

listsinceblock parameter: target-confirmations

As per: https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list We have, [target-confirmations] intentionally does not affect the list of returned transactions, but only affects the ...
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6 votes
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How to minimize risk when accepting zero confirmation payments?

From http://www.cryptocoinsnews.com/news/the-mathematically-secure-way-to-accept-zero-confirmation-transactions/2014/02/13, here is what services like MyCelium and BitPay may be doing: More ...
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6 votes

Why do nodes trust other nodes to approve their transactions?

I know that the blockchain technologie works so well, because everybody has basically a copy of the last ledger. Yes, every full bitcoin node has a copy of the blockchain (aka ledger). Therefore,...
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6 votes

Why can bitcoins never be refunded unless the receiver agrees to send back the money?

Bitcoin is like cash: You don't use an intermediary. If you send money to someone, they got it. The only way you can get is back is to make them hand it to you. If there is no intermediary, you can't ...
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  • 3,154
6 votes
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Why doesn't BTC reward miners for confirmations, too?

I'm not 100% sure I've understood your suggestion, in part because you've used some non-standard terminology. But it looks like this is actually two suggestions rolled into one. The first is a ...
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5 votes
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How long does it take for a transaction with 0 fees to be confirmed or rejected?

The time it takes for a fee-less transaction to be confirmed can vary vastly. While sometimes you're lucky enough to have it confirmed within the next block (as if you had paid the standard fee), ...
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  • 1,394
5 votes
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Why are there so many confirmations?

The number of confirmations indicates under how many blocks your transaction is buried. The more the confirmations, the more your transaction is secure from double-spending attacks. So the ...
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  • 5,114
5 votes
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How do you calculate a reasonable transaction fee?

See https://bitcoinfees.21.co/ for mempool size and tx fee. This will suggest fee in satoshi/byte depending on current network conditions. If you are looking to exact fee in BTC for spending from ...
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  • 1,892
5 votes
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How would one monitor an address for a transaction and 1 confirmation in PHP?

Cron Jobs and 3rd Party API: You could try with cron jobs, but I wouldn't run it every second, that's rather exhaustive. Maybe every 5 or 10 minutes, and then have it check the current total ...
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  • 5,223
5 votes
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Does desktop wallet need to be online for the coins to mature?

No, your wallet does not have to be online. Maturity depends on the block number in which a transaction was included into the blockchain.
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5 votes

Does desktop wallet need to be online for the coins to mature?

Receiving bitcoins is a completely passive process: The information of the received transaction gets added to the blockchain enabling you to reference it in the future when you want to spend the ...
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  • 63.4k
5 votes

What is the "confirmation" field in a block?

The concept of confirmation in Bitcoin is a measure for how deeply buried a block or transaction is in the blockchain. It measures how many blocks on top there are. More means the block or transaction ...
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