I am using bitcoin Qt version v0.7.0-beta and when I tried to send a transaction (1.5 bitcoins) I received a message

transaction creation failed

what can be the reason? Few minutes ago I sent 0.1 bitcoins and it was accepted. Three hours ago I sent 0.3 bitcoins and it was accepted and received on the other side.

I tried to restart the wallet but this still happens.

P.S. I do have more than 1.5 bitcoins when I am trying to send them.

Just a few observations. I tried to send 0.3 and 0.5 bitcoins one more time and it works with both of them.

Just tried one more time to transfer some bitcoins to another account in BitCoin Qt (version v0.8.3-beta - the newest at the time of writing).

This time I am getting some additional error message, which is still is not useful.

Transaction too large

and right after it another one

Error: Transaction creation failed!

P.S. just few days ago I updated the client to v0.8.5-beta but the problem still exist. I really want to spend my bitcoins, but can not do this. I also tried different addresses.

2 Answers 2


Transaction too large

Is your wallet made up up of many, many small amounts? Have you visited any sites giving small amounts of Bitcoin away for "free"? If so, your client is coughing up on the fact that all the small transactions are costing more than the fee they incur to spend.

  • Mostly I received coins through mining. But I also was trying some free bitcoins services. Looking through history I see that I received some (~ 10) coins through micropayment. It sounds strange to me that the client refuse to use them, because with normal money I can spend them even if I have 100$ in cents. Commented Sep 29, 2013 at 13:09
  • Transactions become more complex if they need to combine many input coins, and the entire world must validate them when they enter the block chain. Because of this, some limitations exist on the size of created transactios. You can first try sending smaller amounts to yourself, to combine the inputs already partially. Commented Sep 29, 2013 at 15:06
  • thanks @PieterWuille any idea how I can do this? Commented Sep 29, 2013 at 18:20

You have to spend your bitcoins in small amounts. I don't think there is any other way. Try to send as large as possible to pay less fees.

This piece of code is preventing QT from sending transactions that are larger than 100Kb.

unsigned int nBytes = ::GetSerializeSize(*(CTransaction*)&wtxNew, SER_NETWORK, PROTOCOL_VERSION);
                    if (nBytes >= MAX_STANDARD_TX_SIZE)
                        strFailReason = _("Transaction too large");
                        return false;
                    dPriority /= nBytes;


  • This mean that if I will compile my own client (with blackjack hookers and without this part), I will be able to send them properly. But will this transaction be propagated? Commented Oct 1, 2013 at 14:31
  • 3
    I don't think so. You will probably be able to create the transaction but fail at propogating to peers. Because there are similar checks like this for propogating. Even if you change the propogation methods too and propogate to peers, your peers wont propogate and the tx will fail.
    – Emre K.
    Commented Oct 1, 2013 at 19:25

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