Question about confirmations and reorg

[Do-DMT]

Hi guys (and gals? )

So here's what I'm Wondering;
After a transaction is made, is there any chance it won't be confirmed at all? If so, what would cause it not to be and what are the odds of that?
If there's a re-org and the transaction goes back into the mem-pool, would it be confirmed automatically later?

Also, what was the longest period of time you had to wait for a confirmation?
I once made a transaction that took almost a day for it to be confirmed, and if I remember right it also took a long time until it even appeared in the recipient's wallet. could it have been the result of a bad wallet? It was about a year ago so I don't think the network was very busy.

Thanks!

[ranochigo]

After a transaction is made, is there any chance it won't be confirmed at all? If so, what would cause it not to be and what are the odds of that?

Yes. Miners can choose to not include it. There can be a whole lot of factors as to why miners would not want to include it; non-standard transactions, fees are too low, miner's preference, etc. No one can really tell you the odds of it happening; generally miners do not actively exclude specific transactions and non-standard transactions should not happen if your wallet is functional. I vaguely recall there's one mining pool that mines non-segwit transactions exclusively.

For it to be never included in the block signifies that all of the miners collectively do not want to mine it and it's almost always because it is invalid or non-standard.**

If there's a re-org and the transaction goes back into the mem-pool, would it be confirmed automatically later?

Depends. See above, it'll only be confirmed if it's included in the block in the longest chain.

Also, what was the longest period of time you had to wait for a confirmation?

Weeks.

I once made a transaction that took almost a day for it to be confirmed, and if I remember right it also took a long time until it even appeared in the recipient's wallet. could it have been the result of a bad wallet? It was about a year ago so I don't think the network was very busy.

Possible. How much fees did you pay? The minimum fees for a good propagation is 1sat/vbyte and can increase depending on the mempool capacity (which I assume isn't the case). Poor propagation is not all that common anymore, what wallet are you using?

*Non-standard transactions can still be included in a block but they require explicit participation from a miner that is able to mine a block.

[DannyHamilton]

Hi guys (and gals? )

Hi.

So here's what I'm Wondering;
After a transaction is made, is there any chance it won't be confirmed at all?

Yes.

If so, what would cause it not to be

• Insufficient fee
• invalid transaction
• poorly connected wallet

and what are the odds of that?

• Nearly zero if you pay a sufficient transaction fee
• Nearly zero if you use well written and reviewed open source wallet software
• Very, very low as long as you can access pretty much everything else on the internet

If there's a re-org and the transaction goes back into the mem-pool, would it be confirmed automatically later?

Almost certainly.  That's WHY it went back in the mem-pool instead of being deleted. However, in MOST cases, it will already be confirmed in the re-org.

Also, what was the longest period of time you had to wait for a confirmation?

Three weeks, because I INTENTIONALLY paid an insufficient transaction fee. I was not in a hurry, and just kept re-broadcasting the transaction until transaction fee requirements dropped.

I once made a transaction that took almost a day for it to be confirmed, and if I remember right it also took a long time until it even appeared in the recipient's wallet. could it have been the result of a bad wallet?

Depends on the wallet you and the recipient were using.  Perhaps they were using a wallet that only displayed CONFIRMED transactions? Perhaps you were using a wallet that did a poor job of fee estimation?  It's also possible that the required fee for a fast confirmation suddenly increased immediately AFTER you sent the transaction.  This is why I like to use wallets that support RBF.

It was about a year ago so I don't think the network was very busy.

Or, maybe it was.

[odolvlobo]

Also, what was the longest period of time you had to wait for a confirmation?

There are currently hundreds of low-fee transactions that have been waiting for a month to be confirmed.

[Do-DMT]

non-standard transactions, fees are too low, miner's preference, etc. No one can really tell you the odds of it happening; generally miners do not actively exclude specific transactions and non-standard transactions should not happen if your wallet is functional. I vaguely recall there's one mining pool that mines non-segwit transactions exclusively.

For it to be never included in the block signifies that all of the miners collectively do not want to mine it and it's almost always because it is invalid or non-standard.**

what's a non-standard transaction?
could a fee be too low if I kept the default fee, using a good wallet? Or would it only happen if I lowered the fee myself?

Weeks.

What fee did you pay?

Possible. How much fees did you pay? The minimum fees for a good propagation is 1sat/vbyte and can increase depending on the mempool capacity (which I assume isn't the case). Poor propagation is not all that common anymore, what wallet are you using?
*Non-standard transactions can still be included in a block but they require explicit participation from a miner that is able to mine a block.

don't rememeber which transaction was it, it was either 1980sats for a 1262500sats transfer, or a 3936 fee for a 9900000 transaction..one or the other, using edge wallet.
is edge a recommended wallet, or is it just good for noobs?

[Do-DMT]

• Insufficient fee
• invalid transaction
• poorly connected wallet

is there a list of such bad wallets to beware of? or a list of 100% good wallets?

Very, very low as long as you can access pretty much everything else on the internet[/li][/list]

what do you mean?

If there's a re-org and the transaction goes back into the mem-pool, would it be confirmed automatically later?

Almost certainly.  That's WHY it went back in the mem-pool instead of being deleted. However, in MOST cases, it will already be confirmed in the re-org.

so I can conclude that if I pay a solid fee amount and wallet is not faulty, the odds of the transaction being confirmed are > 99.99%?
and the say there's a re-org, which is also rare (1/2000 blocks? less?), then still, it will almost certainly be confirmed eventually
which would make the total odds extremely low.

Three weeks, because I INTENTIONALLY paid an insufficient transaction fee. I was not in a hurry, and just kept re-broadcasting the transaction until transaction fee requirements dropped.

which wallets can make you do that?

[ranochigo]

what's a non-standard transaction?
could a fee be too low if I kept the default fee, using a good wallet? Or would it only happen if I lowered the fee myself?

Non-standard transactions are transactions that are not relayed by the nodes but are otherwise perfectly valid and are able to be mined. An example would be a transaction having 10 satoshis as one of it's output. It is a non-standard transaction as that is defined as dust. Another example would be sending a transaction without fees, etc.

Each wallet has their own individual fee estimation and it is impossible to ascertain the accuracy of it. Sudden spikes in transaction volumes are unpredictable and could result in your transaction taking way longer to confirm. More often than not, they are fairly accurate.

What fee did you pay?

1Satoshi/Byte

don't rememeber which transaction was it, it was either 1980sats for a 1262500sats transfer, or a 3936 fee for a 9900000 transaction..one or the other, using edge wallet.
is edge a recommended wallet, or is it just good for noobs?

The transaction fee is independent of the amount of Bitcoins transferred. It is directly affected by the size of the transaction instead.

I have never used Edge wallet. I use Electrum personally and I find it suitable for my use.

[NotATether]

is there a list of such bad wallets to beware of? or a list of 100% good wallets?

You can't make such a list because most wallets are not intentionally bad at doing the things that DannyHamilton mentioned, because all of those are user issues and usually not faults in the wallet software.

Specifically, if a wallet lets you choose a low transaction fee, or in the case of a full node, has settings for managing which peers or nodes it connects to, there are bound to be users who misconfigure all these things and have all sorts of problems with their transactions.

Very, very low as long as you can access pretty much everything else on the internet[/li][/list]

what do you mean?

He means if you are able to avoid common causes of transactions staying unconfirmed (using low fees, spending unconfirmed inputs in a transaction, and find resolutions for a stuck unconfirmed transaction like rebroadcasting it, removing it from your wallet/node's history and broadcasting another with low fees, using a paid transaction accelerator like ViaBTC's, etc etc (and you can find all this info on the internet) then you will have no problem getting your transactions to confirm.

so I can conclude that if I pay a solid fee amount and wallet is not faulty, the odds of the transaction being confirmed are > 99.99%?

Yes. (barring a failure of the wallet software and full nodes to broadcast your transaction)

and the say there's a re-org, which is also rare (1/2000 blocks? less?), then still, it will almost certainly be confirmed eventually
which would make the total odds extremely low.

A re-org that invalidates a block your transaction is included in just puts it back into the mempool so this case should be treated no differently than a regular unconfirmed transaction.

Three weeks, because I INTENTIONALLY paid an insufficient transaction fee. I was not in a hurry, and just kept re-broadcasting the transaction until transaction fee requirements dropped.

which wallets can make you do that?

Electrum, Bitcoin Core, Mycelium for android, many exchanges and web wallets like blockchain.com, Bitamp, Cryptonator and many more which I haven't used.

[Theb]

so I can conclude that if I pay a solid fee amount and wallet is not faulty, the odds of the transaction being confirmed are > 99.99%?

This is pretty much a guaranteed transaction as long as you provide a sufficient fee for your transaction. Just be careful how much you will put on as a fee as you might end up having your transaction not being taken by any miner because of having a low fee. If you want a good estimate on how much Bitcoin/byte you can give and the time estimated that it will be confirmed you can go to Bitcoin fee calculator websites such as this one as a basis on which you think is an ideal fee as well as the waiting time you can stomach in for the transaction, you should take note that this are just rough estimates and it might not give you the expected time of your transaction being confirmed.

[PrimeNumber7]

If there's a re-org and the transaction goes back into the mem-pool, would it be confirmed automatically later?

Almost certainly.  That's WHY it went back in the mem-pool instead of being deleted. However, in MOST cases, it will already be confirmed in the re-org.

so I can conclude that if I pay a solid fee amount and wallet is not faulty, the odds of the transaction being confirmed are > 99.99%?
and the say there's a re-org, which is also rare (1/2000 blocks? less?), then still, it will almost certainly be confirmed eventually
which would make the total odds extremely low.

If you are spending outputs that are all confirmed, are using the default settings of major wallet software, and include a fee that is consistent with the market rate for transactions to be included in blocks, for all intents and purposes, your transaction will eventually get confirmed. There is the chance that, after you broadcast your transaction, tx fees suddenly increase substantially and do not come back down, your transaction may not confirm.

If you are using the default behavior of a major wallet software, your biggest concern for your transaction confirming is the transaction fee rate. There are many websites that can estimate the transaction fee rate you should include in order for a transaction to confirm within a certain number of blocks, and they tend to over estimate the necessary transaction fee rate.

Three weeks, because I INTENTIONALLY paid an insufficient transaction fee. I was not in a hurry, and just kept re-broadcasting the transaction until transaction fee requirements dropped.

which wallets can make you do that?

This is custom behavior that some people will employ in order to save on transaction fee costs. Most major wallet software will allow you to do this, but will not do so by default.