Suppose that a miner for some reason has the generation transaction of their blocks not take all the possible coins. This can happen for a variety of reasons, almost all of which are bugs:

  • An off-by-one error makes them think that their block should generate only 25 BTC when we're still at 50 BTC per block
  • Some bug prevents them from noticing a transaction fee; perhaps they were mining and updating the block in parallel using non-thread-safe code.
  • Depending on the answer to this question, they may actually decide to do this on purpose (though I can't think of an answer that would cause this in the vast majority of cases)

I can think of a few possible ways the network would respond, and none really seem ideal.

  • The block could be rejected, just as it would be if it had too much generated.
  • The block could be accepted and the extra coins available for whoever mines the next block (in which case, somebody may do this on purpose to encourage others to mine).
  • The block could be accepted and the extra coins lost.

What actually happens?


2 Answers 2


The block is accepted, and the coins are lost. Poor miner.

Here is a link to the part of the 0.6.3 source which checks this: https://github.com/bitcoin/bitcoin/blob/v0.6.3/src/main.cpp#L1362

Also, this has effectively happened before; block #124724 claimed one satoshi less it than could have.

  • Do you have a source on this, such as the standard client code or documentation?
    – Daniel H
    Aug 28, 2012 at 4:12
  • 3
    If you look at the client code, you'll see it only checks to make sure the output isn't more than the total of all fees plus the block reward. No other checks of the amount are made. Aug 28, 2012 at 7:14
  • 1
    Updated my answer with a link to the source. Aug 28, 2012 at 14:31
  • Wouldn't the coins still be available to be collected by later blocks, as they aren't assigned to any address?
    – Murch
    Aug 21, 2013 at 15:15
  • 3
    @Murch: No. That would have made sense perhaps, but it's not how the rules are - and changing things at this level is extremely hard. Aug 21, 2013 at 21:04

the block #124724 issue seems to be a 49ers thing from star trek due to the block reward number.

the code version from block 0 bitcoin v.0.1.0 still had the original poker part implemented (CPokerDialogBase in line 684 of uibase.h) . and therefore the TNG episodes makes the most sense into explaining why this could have happened.

it has a big advantage cause it enables bitcoin also working for people related to such a time in the past. in this case the wild west times. before the year 1900 what was also shown in the appropriate episode to it. then there is also the fact how Data is involved into all that. the artificial AI android.

see here:


found another example as well:

another gap so to say that i wanna close herby!

in block #526591 was someone only claiming halve the reward


the website owner also linked the incident into this stackexchange entry from above. (what also did lead to the fact me finding this here on stackexchange in the first place and now giving the reader this valuable piece of information)

well it should round the thing up for someone wanna learn more about BTC hence i would even say the information contained on the learnmeabitcoin website should give everyone the reward of becoming a full coiner pretending having read through enough and therefore running the knowledge worth a full coin.

this should therefore also close the cycle and better help others to profit from this technology

another idea would be seeing a resonance for those 6.25 BTC into actual course price. what isnt far away from that actual ones (apprx 65k). meaning 62,5k is relevant to resonate into this incident into the past due to being a tenth in fraction to it for the number itself (without the k).

what would also add to the mentioned episode from star trek as well. due to the fact that it was a 2 episode long thing in span.

in this sense the coins are not lost. they act as a bridge that will stay for everyone finding this information from this website here. while my comment here. helps understanding it better why such things happen.

should do the trick

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