Seven Reasons Behind a Delayed Crypto Transaction Confirmation

Guest post — Jeff Fawkes From the CoolWallet S Community

In the CoolWallet S official Telegram group someone asked a question about a BCH transaction that was “stuck.” How are blockchain confirmations made? What causes them to get delayed from time to time?

1 — Block Propagation Time

This is one of the parameters you may underestimate, however, it is a very important one. When a miner discovers a new block, all other miners who are currently searching for the same block would stop searching and concede it to other miners.

Miners check this block is valid and add it to their local copy of the blockchain. If the block is small, it will propagate fast across the network. For instance, how long does it take to download a 1 MB file? This is the “block propagation time” estimate for bitcoin.

Now, presume that a block was found by two separate miners almost at the same time at opposite sides of the network. This block will simultaneously propagate from two sides. Both miners could have received their reward in BTC for the block.

After two to five minutes, similar blocks will meet each other somewhere in the center of the network. When this occurs, nodes pick up the block that was created earliest and reject the second one. These operations take time and use resources, that ultimately affect confirmation times.

2 — Block Size

Block propagation time partially explains why this parameter affects the speed of confirmations. However, during the 2017 debates over the block structure, it became obvious that some people see block size increases as a plus.

For example, miners can generate blocks bigger than 1 MB in the BCH network, which allows for more transactions. However, even when the network balance is working, it could take up to four hours for miners to generate a new block.

This happened in the BCH network when it was beginning. The network increased the block size but inherited bitcoin’s difficult calculation rules, which led to enormously high block finding times. The issue was quickly patched by the main devs.

On the BTC network, a similar situation took place: the blocks became too small for the growing network of users in the winter of 2017–2018. The network wasn’t able to fulfill the public demand on the network. A huge queue of unconfirmed transactions became a reality.

The network was stuck for weeks, leading to a panic sell and the price drop in 2018. The “normal” network fee became around $20-$50 USD. It rarely exceeds 30–50 cents.

3 — Number of Miners in the Network

Obviously, the more miners that are working within the network, the more people will try to take your transaction into a block. If your transaction is not confirmed after two hours, the issue may be that the network has no miners who want to process that given transaction, or even the block itself.

Another thing to note is, miners may use merged or offline mining that led to slower confirmations. These problems tend to affect newer blockchains.

4 — Transaction Fee Set by the User

At the moment, most crypto transactions cost cents. For example, in the BCH network, it costs between 3 to 30 cents. In the BTC network, that can cost up to 90 cents. On the Ethereum network, it is between 10 to 50 cents. If you want your BTC to arrive in the next block, the average fee will be 0.000005 to 0.0001 BTC. If you are happy to wait two to four hours, you can set the fee to 0.000001 or even as low as 0.00000055 BTC.

The higher the fee, the faster the speed of confirmation. Most wallets will try to calculate a fee for you (Exodus) and others offer a choice of pre-defined options (Electrum, Mycelium).

5 — Speed of the Web

It is better to mine cryptos in places where no one can find your farm and ask questions. At the same time, putting a farm in an isolated village sometimes means very poor internet connections. Suppose the block is found in such a far-away corner of the network, it may travel very slowly.

Your own internet speed affects how quickly your wallet recognizes the confirmation. Also, what if your wallet itself needs a reboot? Try to close it and open it again to see if the TX history is refreshed or not.

6 — Mempool Bloat

The mempool is a special place where the network stores all the transactions in a queue. If the block size of 1 MB is not enough to cover all the transactions made over the last ten minutes, some transactions are left in the mempool.

People constantly send coins and the queue of unconfirmed TX’s may grow to a few days. The mempool itself has the built-in ability to reset every three days. This means that if your transaction missed the train, it will simply disappear after three days of waiting and the coins will return to your wallet. This poses a new risk–a zero-confirmation double-spend attack risk.

One way or another, the probability of such a scenario is very low and depends on many factors, including those covered in this post.

7 — Spam on the Network

It is not a big secret that the Bitcoin network has suffered what effectively are spam attacks. To perform one, you need to constantly send lots of small transactions with low fees from one address to another, under your own control. They often call these spam TX’s.

This possibility can be used as a pressure tool in wars against competing cryptocurrencies.

Have you recently had any issues with transaction confirmations? Describe them below.