I'd like to do RBF testing on testnet. I'd like to simulate a transaction with too-low fees, aka "stuck" transaction, and then RBF it in various ways.

Problem is, all testnet transactions are added to the next block due to mostly-empty mempool and 1 sat/B fee rate.

Is there a clever way to create a transaction that sits in the testnet mempool, which can be later mined after RBF?

Didn't the developers of RBF test their code on testnet?

1 Answer 1


There are 2 workarounds possible:

  1. It takes few minutes for most of the transactions to be included in a block. So, you can prepare all the steps in advance and perform within couple of minutes before this transaction is confirmed.

  2. Broadcast transactions with fee rate below 1 sat/vByte

Change Min Transaction Relay Fee in bitcoin.conf with minrelaytxfee=0.00000001

Either run multiple nodes on testnet with same configuration and add them using addnode or ignore this step.

Create a transaction with createrawtransaction, Enable RBF and specify fee rate below 1 sat/vByte with arguments "replaceable" : true and "fee_rate" : 0.5 in fundrawtransaction

Sign the transaction with signrawtransactionwithwallet

Broadcast the transaction with sendrawtransaction

Check the transaction details using https://chain.so/testnet/btc


Bump fee: bumpfee 42bb96fa5f5812cfd53695f679b69bccaf37fb4d49b78a650e05e0109d92f223

  "txid": "bac13170082c79033d37767e9180d676b05044acf90e41b1a992f76eda97f14e",
  "origfee": 0.00000526,
  "fee": 0.00005616,
  "errors": [

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