What can cause a bitcoin transaction to fail to confirm? I know having a transaction fee of 0 can result in miners not being willing to confirm your transaction. What are some other possible causes?
These are the most common reasons:
Your fee is too low to be included by a miner or too low to be relayed by nodes.
Your client is not properly connected to the network when broadcasting the transaction.
An input your are spending is unconfirmed and will never confirm.
The transaction is too small (less than 5430 satoshi's)