After reading this answer by Pieter about "undo files" I'm wondering what happens with transactions that were included in orphaned blocks but are left out the new blocks when "rolling back". Are they just dropped or do nodes include them in mempool and re-forward them?


When a block is disconnected, its transactions are added back to the mempool (where possible). If the new branch connected afterwards does not remove them again, they remain there, and will be picked up by the block construction code.

| improve this answer | |
  • This is unrelated to the undo files though; those are only for reconstructing the UTXO set. The mempool always contains full transactions. – Pieter Wuille May 27 '19 at 20:52
  • Let me update the title, it may be more useful for future travellers – sr-gi May 27 '19 at 23:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.