1 2017-01-30 20:39:40 <fimp> we're sending dozens of transactions per hour, and when the mempool grows we get this error more and more frequently: "'Error: The transaction was rejected! This might happen if some of the coins in your wallet were already spent, such as if you used a copy of wallet.dat and coins were spent in the copy but not marked as spent here.' "
 2 2017-01-30 20:39:59 <fimp> I suspect it to be caused by change output not being confirmed and it being unable to respend them
 3 2017-01-30 20:40:18 <fimp> Do you agree this is the likely cause and have any thoughts on how to avoid it?
 4 2017-01-30 20:40:52 <achow101> Bitcoin Core has a limit for unconfirmed transaction chains. it limits it to 25
 5 2017-01-30 20:41:23 <fimp> achow101: is it possible to increase? and if we did that, any drawbacks?
 6 2017-01-30 20:41:34 <achow101> so if you are constantly spending unconfirmed change, you will end up with large unconfirmed transaction chains, and after 25, no new transactions in the chain are accepted
 7 2017-01-30 20:41:40 <achow101> you can increase it. It's one of the options
 8 2017-01-30 20:42:18 <fimp> achow101: and that will produce the error I quoted?
 9 2017-01-30 20:42:32 <achow101> yes
10 2017-01-30 20:44:05 <achow101> the options you want are -limitancestorcount=<n> and -limitdescendantcount=<n>. You probably want to set <n> to something very large, like 1000
11 2017-01-30 20:45:59 <fimp> achow101: thanks. So I guess limitancestorcount will allow us to create new transactions. What will limidescendantcount do?
12 2017-01-30 20:46:49 <achow101> it will allow you to have transactions that have a lot of unconfirmed descendants
13 2017-01-30 20:47:28 <fimp> achow101: but when creating the transaction, it has no decendants yet
14 2017-01-30 20:48:48 <achow101> This is the help description: Do not accept transactions if any ancestor would have <n> or more in-mempool descendants (default: 25)