Bitcoin software Transaction malleability is once again affecting the entire Bitcoin network. Generally, this causes a lot of confusion more than whatever else, and results in seemingly duplicate transactions until the next block is mined. This is viewed as these: bitcoin software Your original transaction never confirming. Another transaction, with the exact same amount of coins likely to and from the exact same addresses, appearing. This has an alternative transaction ID. Often, this different transaction ID will confirm, and using block explorers, you might find warnings about the initial transaction being a double spend or else being invalid. Ultimately though, only one transaction, with the right amount of Bitcoins being sent, should confirm. If no transactions confirm, or more than one confirm, then this probably isn't directly linked to transaction malleability. However, it absolutely was realized that there have been some transactions sent which have not been mutated, and also are failing woefully to confirm. The reason being they depend on a prior input that also won't confirm. Essentially, Bitcoin transactions involve spending inputs (which can be thought of as Bitcoins "inside" a Bitcoin address) and then benefiting from change back. For instance, if I had an individual input of 10 BTC and wanted to send 1 BTC to someone, I would create a transaction the following: 10 BTC -> 1 BTC (to the user) and 9 BTC (back to myself) In this way, there is a kind of chain which can be made for all Bitcoins from the original mining transaction. blockchain When Bitcoin core does a transaction such as this, it trusts that it can get the 9 BTC change back, and it'll because it generated this transaction itself, or at minimum, the entire transaction won't confirm but nothing is lost. It could immediately send on this 9 BTC in a further transaction without waiting on this being confirmed because it knows where the coins are going to and it knows the transaction information in the network. However, this assumption is wrong. If the transaction is mutated, Bitcoin core may end up trying to produce a new transaction utilizing the 9 BTC change, but based on wrong input information. The reason being the specific transaction ID and related data has changed in the blockchain. http://www.blockchainsoftware.com.au/