user128923: How do I resend a transaction with RBF on a Bitcoin Core node v.19 or v.20? I am running it on Ubuntu.
I tried bumpfee txid and got the response that “the transaction is not BIP125 replaceable”. What does that mean?

user-1: According to BIP 125 which is implemented in Bitcoin Core with one exception, only transactions that signal RBF will be replaceable later with higher fee rate and fee.
You can enable RBF for all wallet transactions using walletrbf=1 in bitcoin.conf file however it should be enabled by default.
In GUI there is a checkbox for RBF which can be used for each transaction:

If you are using RPC commands for creating transaction, most of them have arguments to enable RBF. Example: "replaceable" : true in fundrawtransaction

128923: <p>How do I resend a transaction with RBF on a Bitcoin Core node v.19 or v.20? I am running it on Ubuntu.</p>
<p>I tried <code>bumpfee txid</code> and got the response that “the transaction is not BIP125 replaceable”. What does that mean?</p>
 -1: <p>According to <a href="https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki" rel="nofollow noreferrer">BIP 125</a> which is implemented in Bitcoin Core with one <a href="https://github.com/bitcoin/bitcoin/pull/21946" rel="nofollow noreferrer">exception</a>, only transactions that signal RBF will be replaceable later with higher fee rate and fee.</p>
<p>You can enable RBF for all wallet transactions using <code>walletrbf=1</code> in <em>bitcoin.conf</em> file however it should be enabled by default.</p>
<p>In GUI there is a checkbox for RBF which can be used for each transaction:</p>
<p><a href="https://i.stack.imgur.com/aFAem.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aFAem.png" alt="rbf-checkbox" /></a></p>
<p>If you are using RPC commands for creating transaction, most of them have arguments to enable RBF. Example: <code>&quot;replaceable&quot; : true</code> in <code>fundrawtransaction</code></p>
