Why did my Coinbase transaction take 4.5 hours to get in a block?

Why did this transaction take so long to be put in a block?

I initiated a 7 BTC transfer at 6:13 PM Eastern Time from Coinbase to an external address in an over the counter transaction today. It was put in a block 4.5 hours later (10:42 Eastern Time)

Not conducive to doing business at all :(

I checked /tried these things:

I saw many blocks had been mined since my transaction was initiated at Coinbase.
I saw there was a fee on the transaction
I tweeted an inquiry to Coinbase
I saw Coinbase was connected to 118 peers
I saw other Coinbase transactions posted after mine confirmed within 20 minutes.
I tried to manually broadcast the raw transaction on blockchain
I read Coinbase blog post that they had slow confirms in February.

David Silva Smith

Posted 2013-08-18T05:51:22.997

Reputation: 1 028

I have a transaction that has been pending for about 2 hours. I am also trying to send funds out of my Coinbase account. After some checking on blockchain.info, I think that the problem may be that one of the inputs to my transaction is missing. My transaction is https://coinbase.com/network/transactions/c0a5247e99875b5304fb398619399866e9ae1fb7d3d925d96585ace252bdba2a There are three inputs, including the problem one: 9c2a52bfb51c4e657887e3eb2c7dc413cfd075a9aeed95cf05282b4efec46b96 Blockchain.info has the other two inputs on record. But it does not have 9c2a52b. I checked for that transaction

– Jesse Hallett – 2013-11-03T07:02:32.583

Answers

Brian from Coinbase here. Sorry you experienced delays! There have been some issues in the past that we are working to improve. Coinbase sends a high volume of bitcoin transactions (often in parallel across many machines), and as a result we sometimes encounters issues that are uncommon elsewhere. In this case, I believe the root of the issue was around spending coins where the inputs were not in a block yet. We broadcast a large number of transactions, and sometimes other nodes receive them out of order (the transaction that spends the change could arrive before the transaction that generated the change). The official client, bitcoind, had an issue (unclear whether it was a bug, or intended) where a transaction in the orphan pool that got connected up (it's input transaction finally arrived) did not subsequently get relayed to the rest of the network like a regular transaction. We've been chatting with Gavin about this to see what solutions could make it into a near term release.

An issue like this could cause it to not be relayed to most/many miners, which is why it would take a long time to make it into a block.

As a short term fix we manually push transactions to well connected nodes like blockchain.info to ensure they are well propagated. Thanks for bearing with us as we continue improving things. Experiences like this are definitely not what we strive for. Hope the explanation helps!

Brian Armstrong

Posted 2013-08-18T05:51:22.997

Reputation: 727

Thanks for the follow up! I had this happen two more times later. Once was trying to purchase a domain name around November. Took around a day to workout BitPay (they were great, I had to keep checking if the transaction had been put in a block yet). From these experiences I can't use coinbase for business transactions because a limbo state is the worst state of all. – David Silva Smith – 2014-01-03T12:45:49.050

Coinbase has been hit-and-miss for me for the past month. For example I've had: 1 "instant transfer/buy" that took 23 hours for the coins to arrive. The next day, before my original purchase arrived I needed to make a small additional order to compensate for a rate drop and that one went through right away.

More recently I've had outgoing transfers that took a few hours to appear on the blockchain including one that took nearly 24 hrs again.

For the most part they did not respond to support requests until after the issue was resolved. No acknowledgement to tweets @ them.

Eventual support email was the same form letter each time:

Sorry about the delay! We had an issue syncing >with the blockchain which resulted in >unconfirmed transactions that remained in the >pending state for too long. Now these >transactions have been pushed through - let me >know if you still need help with anything. Again, >my apologies for any undue stress this has >caused!

At the risk of being flagged for "not an answer," to me that doesn't sound like the whole truth but that's all they're disclosing.

Neil Neyman

Posted 2013-08-18T05:51:22.997

Reputation: 598

Thanks! It was a bad situation for me (and probably you). I noticed their support site says 'transaction will be cancelled after 24 hours if unconfirmed' I don't know how that works, but it would be nice to have a cancel button to stop payment and reissue it elsewhere. – David Silva Smith – 2013-08-18T17:04:28.810