<blockquote>
<p>Imagine there are two collision blocks A and B. These are mined at the same time.</p>
</blockquote>
<p>If both miners are neutral, the set of transactions in A is similar to the set of transactions in B.</p>
<blockquote>
<p>One miner created new block C on top of block A and longest chain happened.</p>
</blockquote>
<p>If the third miner is neutral too, it is likely that some transactions in B not in A are in C. And some in A's parent block.</p>
<blockquote>
<p>Do transactions of block B go back to mempool immediately after being created block C?</p>
</blockquote>
<p>See <a href="https://bitcoin.stackexchange.com/a/109920/126793">https://bitcoin.stackexchange.com/a/109920/126793</a>, attention at what is commented there: <code>New transactions start as UNCONFIRMED. At BlockConnected, they will transition to CONFIRMED. In case of reorg, at BlockDisconnected, they roll back to UNCONFIRMED.</code>.</p>

CC BY-SA 4.0
2023-11-16T11:44:01.580Z
What if miners are not neutral (as usually the case)?
nikicat
CC BY-SA 4.0
2021-10-16T07:56:36.337Z
2021-10-16T07:56:36.337Z
Mercedes
<p>Imagine there are two collision blocks A and B. These are mined at the same time.
One miner created new block C on top of block A and longest chain happened.</p>
<p>Do transactions of block B go back to mempool immediately after being created block C?</p>

<blockchain><proof-of-work>
When transactions of orphan block go back to the mempool?
pepperoni
# When transactions of orphan block go back to the mempool?

(Asked by: username_0 on 2021-10-16)

Imagine there are two collision blocks A and B. These are mined at the same time.
One miner created new block C on top of block A and longest chain happened.

Do transactions of block B go back to mempool immediately after being created block C?

**Tags:** blockchain, proof-of-work


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## 1 answers

### Answer by username_1 on 2021-10-16. Score: 1

> Imagine there are two collision blocks A and B. These are mined at the same time.

If both miners are neutral, the set of transactions in A is similar to the set of transactions in B.

> One miner created new block C on top of block A and longest chain happened.

If the third miner is neutral too, it is likely that some transactions in B not in A are in C. And some in A's parent block.

> Do transactions of block B go back to mempool immediately after being created block C?

See <https://bitcoin.stackexchange.com/a/109920/126793>, attention at what is commented there: `New transactions start as UNCONFIRMED. At BlockConnected, they will transition to CONFIRMED. In case of reorg, at BlockDisconnected, they roll back to UNCONFIRMED.`.

> **Comments:**
> **username_2**: What if miners are not neutral (as usually the case)?  

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