Bitcoin Forum

Hi,

I sent some bitcoin using Electrum wallet. In the history tab, I got this yellow exclamation mark next to my transactions saying: Unconfirmed Parent

Here's the screenshot

https://imgur.com/a/NGDsgS5

I tried increasing the fees but then it says:

the server returned an error when broadcasting the transaction. Consider trying to connect to a different server, or updating Electrum

insufficient fee, your transaction is trying to replace another one in the mempool but it does not meet the rules to do so. Try to increase the fee.

This is the screenshot

https://imgur.com/a/901dHx9

I've done the following:
Connect to another server in electrum
update electrum to the newest version
use a free bitcoin accelerator to rebroadcast the transactions
The original fee is 2 sat/b, I tried increase fees a few time and managed to changed that to 6,7,and 14 sats/b respectively

But the transaction still not getting any confirmations

Transactions can only be confirmed when their parent transaction is confirmed. Certain miners would mine both the child and the parent transaction if the fees are high enough.

You would probably need a much more fees for a fast confirmations and without the details of the transaction it would be hard to estimate how much is required. Do you mind sharing the transaction IDs?

Mempool is full (https://jochen-hoenicke.de/queue/#0,24h): you currently need more than 12 sat/vbyte for a fast confirmation.
If you're not in a hurry: just wait. Chances are mempool clears over the weekend, and your transactions will confirm.

I think this means your increased fee is too close to your previous fee. Note that increasing the fee for your first transaction invalidates the later (child) transactions.

As far as I understand, you already have one unconfirmed transaction and you are trying to send another or the you have an incoming unconfirmed transaction and you are trying to send it while it's still unconfirmed?

Either way, you just need to wait for that unconfirmed transaction to get atleast 1 confirmation before you can send your balance. That yellow exclamation is a sign that the source of your funds is still not confirmed on blockchain.

It can be both.

If there is an unconfirmed parent then you can use CPFP (Child Pays For Parent) meaning (more or less) that your transaction has a high enough fee that a miner will also mine one of the incoming (parent) transactions.

If you sent the transaction with a fee high enough that a miner will not want to include the parent then you have to wait.

If you do not have RBF (replace by fee) set to on then once you broadcast that transaction it's out there, you cannot add a larger fee to get it confirmed more quickly.

I'm on mobile so I can't see the images.

If you give the TXID others can probably help more.

-Dave

Here's the amount of bitcoin I tried to sent

First transaction (Unconfirmed parent): 0.00051675 BTC
Second transaction(Unconfirmed parent): 0.00047 BTC
Third transaction(Unconfirmed): 0.00021227 BTC

The amount doesn't matter. Take the total fees of all of the transactions and divide by their size. For example:

If TX 1 is paying 1000 satoshis in fees, 300 bytes, TX 2 2000 satoshis in fees, 400 bytes, TX 3 4000 satoshis in fees, 400 bytes. Then the effective TX fees across all of the transactions would be 7000/1100: 6.3 satoshis/byte. If the result of your calculation isn't at least 12 satoshis/byte then you probably won't get a confirmation so soon.

Yeah, when I tried increase the fees and set it further from my previous fee, it got changed

I normally set the fee to 2 sat/b, and it takes around 1 hour to get confirmed. This is the first time I set the fees higher but still not getting confirmation in 2 days

I haven't understood what you said 'Note that increasing the fee for your first transaction invalidates the later (child) transactions'

Transaction 1 (Unconfirmed parent)

Fees   : 0.00002016 BTC (14.3 sat/vB)
Size:   223 B
Virtual Size: 142 vB

Transaction 2 (Unconfirmed parent)

Fees: 0.00000929 BTC (6.6 sat/vB)
Size:   222 B
Virtual Size: 141 vB

Transaction 3 (Unconfirmed)

Fees: 0.00001008 BTC (7.0 sat/vB)
Size:   225 B
Virtual Size: 144 vB

Assume that you have sent bitcoin from address A to address B and then sent the same coin from address B to address C.
If you bump the fee of the transaction made from address A to address B, the transaction made from address B to address C becomes invalid.


The total virtual size of your transactions is 427 vbyte and the total fee paid for three transactions is 3953 satoshi.
This means that the effective fee rate is around 9 sat/vbyte.
Your transactions are now around 45 vMB from the the tip and you shouldn't expect them to be confirmed soon.

If you are in hurry, bump the fee of transaction 3.
Currently, for a fast confirmation, the fee of around 20 sat/vbyte is required.
Given the total size of your transactions are  427 vbytes, you should pay 8540 satoshi in total.
You have paid 2945 satoshi for the first two transactions and you need to pay 5595 satoshi for the third transaction. So, you need to bump its fee to 38 sat/vbtye.

Again, if you are not in hurry, just wait.

Edit:
I assumed that transaction 3 is spending the fund received in transaction 2 and transaction 2 is spending the fund received in transaction 1.

My wallet has enough funds to make the 3 transactions above, there's no ongoing pending transactions before I made any of the 3 payments. I don't understand why the 'Unconfirmed Parent' occurred

An input that you used is unconfirmed. Check the transaction details and you'll realize that if you check the inputs of the transactions with unconfirmed parent, at least one of the input is unconfirmed.

Yes, 'replace by fees' is on for all 3 transactions

A few points I haven't understood:

How do I do a CPFP?

You said the fees need to be high enough so miner will mine one of the incoming (parent) transactions, but you mentioned miner will also not want to include the parent if my fee is high enough. I am a little confused

If you're on Electrum, right click on the unconfirmed transaction -> Child pays for parent -> Enter the fee you're willing to pay on "Fee for child:" and click "OK". You'll have to be a little bit more generous to encourage the miner include both.

That's the high fee currently: https://blackhatcoiner.com/highfee/ (https://bitcointalk.org/index.php?topic=5366056.0)

The first 2 transactions are marked as 'Unconfirmed Parent' and the third transaction is marked as 'Unconfirmed'. What's the difference, do they link with each other ?

Initially, my wallet have enough fund to make these 3 payments, they should be coming out independently, don't understand why 2 of them are 'Unconfirmed Parent'

I remember I made the third transaction first (the Unconfirmed one), I made the other 2 transactions (Unconfirmed Parent) after that, but not sure which one of the 2 I sent first.

When electrum says that a transaction has unconfirmed parent, it means that the fund which is being tried to send in that transaction has been received in a transaction which is still unconfirmed.

Assume that you have sent bitcoin from address A to address B and then the same coin from address B to address C.
As long as the transaction made from address A to address B is unconfirmed, the transaction made from address B to address C can't be confirmed.

The two transactions that have been marked as "unconfirmed parent" can't be confirmed before confirmation of their parent.

Can you share your transactions IDs?
With sharing your transactions, you may hurt your privacy. But it won't have anything with your security.

I open the details for all 3 transactions, each has inputs and outputs

There's one output in transaction 3 (Unconfirmed) is the same as one input in transaction 1(Unconfirmed Parent)

There's one output in transaction 1 (Unconfirmed Parent) is the same as one input in transaction 2(Unconfirmed Parent)

What are the relationship of these 3 transactions ?

Transaction 3 -> Transaction 1 -> Transaction 2.

For transaction 1 to have a confirmation, transaction 3 has to confirm first. Afterwhich, for transaction 2 to confirm, transaction 1 has to have a confirmation first.

What kind of transaction are these for; for a payment, a transfer to someone, a transfer to yourself? You can choose to create yet another transaction(which is mentioned above) or to have a replace-by-fee on transaction 3 which will invalidate transaction 1 and 2. Afterwhich, you can choose to create a new transaction that is similar to transaction 3 and continue with transaction 1 and 2.

Replace-by-fee is cheaper than CPFP.

Right

I made transaction 3 first, then 1 and 2 (not remember the order between 1 and 2)

Is transaction 3 (Unconfirmed) the parent for transaction 1 and 2 (Unconfirmed Parent)

As mentioned by ranochigo, you have made the transaction 1 before transaction 2.
If you want these transaction to be confirmed fast, you should bump the fee of transaction 2

Note that with bumping the fee of transaction 3, you invalidate transactions 1 and 2 and with bumping the fee of transaction 1, you invalidate transaction 2.

Yeah, this order sounds about correct

Transaction 3 is a transfer to someone
Transaction 1 and 2 are for payments to 2 different vendors

So right now, I will need to get transaction 3 confirmed first, then repost transaction 1 and 2, right ? If transaction 3 doesn't get a confirmation, transaction 1 and 2 would never go through

I'm now trying to increase the fees for transaction 3. The current fee for transaction 3 is 7 sat/b, but even I put in 27 sat/b, it still says:

the server returned an error when broadcasting the transaction. Consider trying to connect to a different server, or updating Electrum

insufficient fee, your transaction is trying to replace another one in the mempool but it does not meet the rules to do so. Try to increase the fee.

If you are in hurry, bump the fee of transaction 2.
If you are not in hurry, just wait.

As calculated, the total virtual size of your transactions is 427 vbyte.
Given that for a fast confirmation, transaction fee of around 14 sat/vbyte is required, you need to pay 5978 satoshi in total.
You have paid 3024 satoshi for transactions 1 and 3 and need to pay 2954 satoshi for transaction 2.
If you are in hurry, bump the fee rate of transaction 2 to 21 sat/vbyte.

You can pay a bit more (around 25 sat/vbyte) to make sure your transaction will be confirmed soon. The fee rate required for a fast confirmation changes over time.


With doing so, you invalidate transactions 1 and 2.
If you want all three transactions to included in the blockchain and you are in hurry, bump the fee of transaction 2.

Note that in my previous post, I had assumed that the order is transaction 1 ---> transaction  2 ---> transaction 3 and that was why I said you should bump fee of transaction 3.
Since the order is transaction 3 ---> transaction 1 ---> transaction 2, you should bump fee of transaction 2.

Again, no need to do anything, if you are not in hurry.

I set the fees to 30 sat/b, and now it changed

At the same time, it shows that transaction 1 and 2 are invalidated

The transaction made with fee rate of 30 sat/vbyte will be likely confirmed in the next block. (A new block is mined every 10 minutes on average)
Transactions 1 and 2 no longer exist.

It's fine, I might just redo transaction 1 and 2 later

I think the problem here is the 3 transactions are somehow linked with each other, which creates a chain reaction. This was never my intention though when I sent them yesterday. I just wanted to send 3 transaction to 3 different address, they should be independent and not interfere with each other

Do you know why this would happen? so I can avoid this situation in future payments

Additionally, how do you calculate what fees to set, do you refer to a website ?

For the next time: if possible, using "Pay to many" in Electrum gives you lower total fees. You'll have one transaction with multiple outputs and only one change address.

That's how a blockchain works: each transaction uses the output from the previous transaction.

If you have multiple inputs in your own wallet you can use Coin control to avoid this, but you don't need to. It's normal.

I always use Johoe's Bitcoin Mempool Statistics (https://jochen-hoenicke.de/queue/#BTC,24h,weight).
To know the current required fee, hover your mouse cursor over right side of the chart.

Look at the screenshot I just took.

https://i.imgur.com/vZhXkcR.jpg


The total virtual size of transactions paying at least 1 sat/vbyte is 100 vMB.
The total virtual size of transactions paying at least 2 sat/vbyte is 52 vMB.
The total virtual size of transactions paying at least 3 sat/vbyte is 49 vMB.
...........
...........
...........
The total virtual size of transactions paying at least 17 sat/vbyte is 0.91 vMB.

Note that miners prioritize transactions based on the their fee rate and every block has a capacity of 1 vMB.
So, if I set the transaction fee to more than 17 sat/vbyte, my transaction will likely be confirmed in the next block.
Note that it's possible that new transactions with higher fee rates are added to the mempool and my transaction isn't confirmed in the next block. So, I can pay a bit more (18-20 sat/vbyte) to increase the chance of getting confirmation in the next block.

There are other websites like mempool.space (https://mempool.space/) that can be used to estimate the required transaction fee rate.

Right

The 'Pay to many' option can keep multiple transactions at the same position, right ? So even one transaction doesn't get confirmed, it wouldn't affect other transactions' progress

Didn't find the 'Coin control' you mentioned, where is it in Electrum ?

When you use "pay to many", you pay bitcoin to all recipients in a single transaction and there is no other transaction at all.


Click on "View" at top of the window and select "Show Coins".

I am making another transaction now. I use your method, refer to Johoe's Bitcoin Mempool, and see 14+ is 1.122 vMB, so I set my fee 14.2 sat/vB.

This should mean that my transaction will be in the 2nd block, right ? But I right click the transaction, and view on block explorer, it says in 144 blocks. I check back 10 minutes later, it has improved says still in 16 blocks though.

Additionally, I go to mempool.space, it gives 3 fees, Low priority, Medium priority and High priority. How do I read them ?

Right, so I just need to pay the fee once. And if it's confirmed, all the recipient would receive their bitcoins. This way can reduce cost as well


Yeah, I see a couple of output points, and each has their address and amount. Do they mean that the total fund in my wallet are stored into these addresses ? And I can choose a particular address to make a specific payment

Not necessarily. New transactions will be added to the mempool and they may delay the confirmation of your transaction.


They are just estimations calculated based on network state.


To be more precise:
You can specify which UTXO (coin) you want to be used for your transaction.
Note that any address can contain numerous UTXOs (coins).

Sure, how to use coin control to make a payment?

I right-clicked on one of the output points, and select Spend, saw that line turns green

After selecting, click Send tab.
Use ctrl to select more than 1.

Do you mean after I click 'Spend' on one output point, I just go to the send tab, and make a transaction as usual. Then the coin will only come out of that particular 'control coin balance'

Yes. It's also good practice to always preview your transaction before sending. You can enable that as default behavior somewhere in Electrum's settings.
When previewing, check them inputs, outputs and fee.

OK, thanks!