You can download that file on a computer connected to the internet. Make sure to verify the signature. And then transfer it to your "Cold System".

Or if you know what you are doing, run a fresh Linux (eg Ubuntu) download the file, disconnect and never connect again. And install there.

To receive BTC your only give your public key (the bitcoin address starting with 1 or 3) to anyone and ask them to pay you. There is nothing else you need to do apart from seeing your balance go up

To spend BTC you take multiple steps:
1. create the raw unsigned transaction
2. move that to cold storage and sign it there
3. move the signed tx back to an online computer and broadcast it.
It is actually easier than it sounds but you need to try it at least once with small amount (eg 0.0001BTC) to get the hang of things
More details: http://docs.electrum.org/en/latest/coldstorage.html

A cold storage or and offline system that you use should have always been offline and always remain offline in the future too. That means if it was online once before or if you plan on connecting it to the internet in the future or practically connecting anything unsafe to it, then that is no longer a cold storage and your safety may have been compromised.
That doesn't mean it is though! I have a hot wallet on my desktop and I am fine.

So for this part
If you are doing it on a system that has been online before and you are just disconnecting the internet then there is no difference.

What you should do is that you should go on a fresh system and do all the wallet creation. It can be another old computer with no internet access and a freshly installed OS. Or a simpler way is to just run a live linux. You can run it from a CD or your USB disk with your router/modem off, then create the wallet and write down the seed, turn that linux OS off to lose all the data and just have that piece of paper as your wallet.

There are a lot of other things that can be don, search for cold storage or ask here if you want more details.

I couldn't load that website for some reason (I blame my internet provider ), and it is because of your rank that it doesn't show up (it is a forum thing).

[sorry it took too long I was booting up my Ubuntu to make the screenshots with 2.8.1]
This is basically what happens with each option.
Never is obvious.
Always is obvious too.
The middle option "If fee is low" activates the "Replaceable" checkbox to let you make the transaction replaceable only if your fee is lower than the threshold.

Yup, that thing needs a little bit of explanation. I took the liberty of opening up a new issue about this and another GUI bug that bugged me for some time https://github.com/spesmilo/electrum/issues/2312

I can't see that picture. If it is showing the preference window it is ok to show it, anything else such as your bitcoin addresses can ruin your privacy and obviously showing the seed or private keys is just going to let others rob you (the last three can be in QR code and some people miss that when they make a screenshot)

You don't need to worry about appropriate fees. The wallet takes it from the servers and suggests the best/appropriate fee. Use the slider to see.

(oops this is 2.7.17 but I don't think they changed anything about this in 2.8.1)

When you receive fund it is up to the sender (in this case Bitstamp) to pay appropriate fees.
You can't adjust the fees and also it is strange that you are waiting for that transaction to confirm since network load (number of unconfirmed transactions in the memory pool) has been very low these days.

Please update us in the future in case you found out why this was happening or in case it was fixed.
Thanks.

As I said one way is that link above (https://blockchain.info/unconfirmed-transactions).
There are also other exchanges:
https://www.smartbit.com.au/ or the page https://www.smartbit.com.au/txs you can also change the unit to USD from top right corner.
https://live.blockcypher.com/btc/ Doesn't have USD though!
http://fiatleak.com/ is also a neat site.

You can also use blockchain.info sockets (https://blockchain.info/api/api_websocket) you need to subscribe to {"op":"unconfirmed_sub"} then you can process the transactions however you like and display them yourself

Can you explain what is it exactly you are trying to do?
Any transaction you may have had, is either dropped out of mempool already and you can send it out by creating a new transaction or it is confirmed. The mempool was empty for the past 24+ hours and miners are including very low fee transactions.

And if you double spend and try broadcasting the second transaction I believe nodes will reject it if they have the first transaction in their mempool and it is not signalling RBF.

May I ask why you want the scrolling transactions in the blockchain.info home page?
And yes there is a way to see that apart from that link.

Correct me if I am wrong but there is nothing in the protocol that prevents you from making bigger transactions. And I can think of at least one transaction from 2015 that was nearly 1000000 bytes (~1 MB) and it was mined with no problem.

Currently this feature is not available yet.
But the suggestion is already made to the developers: https://github.com/spesmilo/electrum/issues/1568

Try renaming the file to .JSON

I just checked the imported .dat file from old version and the content seems the same as the new .json file. So try renaming it by changing the extension from electrum_labels.dat to electrum_labels.json and see if that helps.

This feature was moved to coins tab: https://github.com/spesmilo/electrum/blob/master/RELEASE-NOTES#L14


Press Ctrl+A to see the addresses tab.
Also from toolbad Wallet > Addresses and also Wallet > Coins

Sorry have never seen this error before. But I have found this similar issue: https://github.com/spesmilo/electrum/issues/1556

You can set the fee (brc/kb) with the slider or set a manual fee from the text box.


Thomas checks this board.
You can also open an issue on GitHub if you find a bug: https://github.com/spesmilo/electrum/issues/new

Number of tx_ins and tx_outs
In other words if you have multiple outputs (UTXO or transactions to spend) and if you are paying to multiple keys (sending bitcoin to many bitcoin addresses) your transaction size is bigger.
https://bitcoin.org/en/developer-guide#transactions

You can read about the structure of a transaction here (Raw Transaction Format) https://bitcoin.org/en/developer-reference#raw-transaction-format

So when you are spending 1 output and creating 1 new output your transaction size becomes ~225 bytes
example: https://blockchain.info/tx/ee33588fced298248c9e693b4eee72e2aae6963381b63cf5850ba2e94abe2d90?show_adv=true

But when you are spending multiple outputs (for example 10) and create 1 new output your transaction size becomes 1847 (with uncompressed private keys will be smaller with compressed)
Example of 1 output to multiple:
https://blockchain.info/tx/db8b1751c00bce986f833022fb4ed4b55406597eb0c11ad0fb8347765ddbdf39?show_adv=true
Example of multiple outputs:
https://blockchain.info/tx/16398c9e7261ec72c09bc5e5b712049882a7f857e363f9ac591e5a53cf37b410?show_adv=true
* These two were taken from the last block mined


Use a wallet that tells you how much fee is appropriate, there is no need for you to "learn" what the transaction size will be.

This^

Blockchain.info as a block explorer has always been an odd one! It has been a couple of months that they suddenly decided not so show transactions with low/zero fees on their block explorer and your transaction with 226 satoshi fee is considered pretty low so blockchain.info doesn't show it.

And it is odd because as a public service (a block explorer) they shouldn't exclude any valid transaction that is being relayed by nodes even if it has low fees!


If you are running bitcoin core (a full node) why do you even bother with block explorers? Just send the transaction again with higher fees if you don't see it in your wallet!

A wallet that has been around for a couple of years, a couple of developers working on it and more people contributing to the code and checking it for bugs,... and thousands of users using it and reporting any possible bugs and helping the development.

Versus

A wallet that you build, only you code, you test, you secure. All alone.

---

P.S. If you are worried about these stuff there are other ways of "generating a private key" without using any of the wallets, or without a computer even. Check out how to get a random number offline using dice.
Here is an article about it: http://www.swansontec.com/bitcoin-dice.html

There you go:
[Warning][Cloudbleed bug] Change your passwords & 2FA & API keys

Good idea, added "Change 2FA" and "API keys" to the subject and in the TL;DR with red font.

I don't see anyone talking about this here so I'll start it here because of its importance and move it to services discussion later.


TL;DR: Bitcointalk is not affected, there is a small chance exchanges and web wallets are affected. To be safe change your password and enable 2 Factor Authentication if you already had a 2FA key change that too also generate new API keys if you were using those too.



You may have heard about the Cloudflare bug that leaked lots of sensitive information if not read more about the details here:
https://blog.cloudflare.com/incident-report-on-memory-leak-caused-by-cloudflare-parser-bug/

In any case you should change all your passwords on services that were using Cloudflare and are affected by this bug in order to be safe. You can see more information and the list of affected services here:
https://github.com/pirate/sites-using-cloudflare/blob/master/README.md

Also there is a website to check if a website was using Cloudflare (not sure how reliable it is):
http://www.doesitusecloudflare.com/

Name	|	Uses cloudflare (May Be Affected)
Bitcointalk	|	No (does not use Cloudflare)
Bitstamp	|	No (does not use Cloudflare)
Blockchain.info	|	YES
Bitfinex	|	YES
Coinbase	|	YES
Localbitcoins	|	YES
Poloniex	|	YES
Bittrex	|	YES
Kraken	|	YES
Bitpay	|	YES
Btc-e	|	YES
Cex.io	|	YES
C-cex	|	YES
Yobit	|	YES

* These sites may or may not be affected by the bug, but it is safer if you change your password immediately and enable 2FA. Better safe than sorry
** Just checked a couple of gambling sites, and they all use Cloudflare. Not going to list them here since they are of less importance but you have been warned.

Help me complete the table.

Bitcoin core needs to sync by downloading the whole blockchain which is about 100 GB.
- Let it sync... the time it takes depends on your internet speed and your computing power.
- Or use an SPV wallet if you have problems. In that case I recommend Electrum. It will need to download only 35 MB for syncing. Although you will lose the benefits of running a Full Node.

Speak for yourself.
And I seriously doubt that you have ever even invested in bitcoin or get anything apart from your signature spam payment.