<p>Indeed.</p>

<p>Bitcoin Core will, after upgrade to a SegWit-compatible version (0.13.1 and later), rewind to the latest non-SegWit block and then fetch the later blocks again.</p>

CC BY-SA 3.0
2017-08-30T03:03:01.687Z
Will it fetch only the witness data or the entire block?
sanket1729
CC BY-SA 3.0
2017-08-30T03:17:54.627Z
The entire block. There is no P2P protocol for downloading just witnesses.
Pieter Wuille
CC BY-SA 3.0
2017-08-11T17:11:23.307Z
2017-08-11T17:11:23.307Z
Pieter Wuille
<p>Let's suppose I run a legacy (non-SegWit) node after SegWit gets activated. My blockchain doesn't store any SegWit data. What happens when I upgrade my node? Will I have to re-download the blockchain to include the missing SegWit data?</p>

<bitcoin-core><segregated-witness>
Legacy blockchain after upgrade to SegWit
Paul
# Legacy blockchain after upgrade to SegWit

(Asked by: username_0 on 2017-08-11)

Let's suppose I run a legacy (non-SegWit) node after SegWit gets activated. My blockchain doesn't store any SegWit data. What happens when I upgrade my node? Will I have to re-download the blockchain to include the missing SegWit data?

**Tags:** bitcoin-core, segregated-witness


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## 1 answers

### Answer by username_1 on 2017-08-11. Score: 3 | Accepted answer

Indeed.

Bitcoin Core will, after upgrade to a SegWit-compatible version (0.13.1 and later), rewind to the latest non-SegWit block and then fetch the later blocks again.

> **Comments:**
> **username_2**: Will it fetch only the witness data or the entire block?  
> **username_1**: The entire block. There is no P2P protocol for downloading just witnesses.  

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