<p>It should be forward compatible, but making backups of your wallet is always recommended.</p>

<p>Once you upgrade to 0.10.x, downgrading to 0.9.x afterwards may not be possible anymore.</p>

CC BY-SA 3.0
2015-07-03T15:46:35.223Z
Forward compatible, not backward compatible. You can upgrade from 0.9 to 0.10, but not the other way around.
Pieter Wuille
CC BY-SA 3.0
2015-07-03T12:28:07.253Z
2015-07-03T12:28:07.253Z
Pieter Wuille
<p>In the official release announcement here:
<a href="https://bitcointalk.org/index.php?topic=1039713.msg11211433#msg11211433" rel="nofollow">https://bitcointalk.org/index.php?topic=1039713.msg11211433#msg11211433</a></p>

<hr>

<h2>Downgrade warning</h2>

<p>Because release 0.10.0 and later makes use of headers-first synchronization and
parallel block download (see further), the block files and databases are not
backwards-compatible with pre-0.10 versions of Bitcoin Core or other software*</p>

<hr>

<p>So upgrading works fine, but if you later decide to downgrade the block and database files won't be compatible.</p>

CC BY-SA 3.0
2015-07-03T18:42:11.373Z
2015-07-03T18:42:11.373Z
gio44
<p>I have version 0.9.3 of bitcoind on my Ubuntu server and I want to upgrade to 0.10.1,
I have nothing in my wallet.
Does the blockchain 0.9.3 compatible with 0.10.1?
Do I have anything to keep from version 0.9.3 ?</p>

<blockchain><bitcoin-core><ubuntu>
Ubuntu. (blockchain of version 0.9.3 compatible with 0.10.1?)
Patton000
# Ubuntu. (blockchain of version 0.9.3 compatible with 0.10.1?)

(Asked by: username_0 on 2015-07-03)

I have version 0.9.3 of bitcoind on my Ubuntu server and I want to upgrade to 0.10.1,
I have nothing in my wallet.
Does the blockchain 0.9.3 compatible with 0.10.1?
Do I have anything to keep from version 0.9.3 ?

**Tags:** blockchain, bitcoin-core, ubuntu


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## 2 answers

### Answer by username_2 on 2015-07-03. Score: 3 | Accepted answer

In the official release announcement here:
<https://bitcointalk.org/index.php?topic=1039713.msg11211433#msg11211433>

---

## Downgrade warning

Because release 0.10.0 and later makes use of headers-first synchronization and
parallel block download (see further), the block files and databases are not
backwards-compatible with pre-0.10 versions of Bitcoin Core or other software\*

---

So upgrading works fine, but if you later decide to downgrade the block and database files won't be compatible.


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### Answer by username_1 on 2015-07-03. Score: 1

It should be forward compatible, but making backups of your wallet is always recommended.

Once you upgrade to 0.10.x, downgrading to 0.9.x afterwards may not be possible anymore.

> **Comments:**
> **username_1**: Forward compatible, not backward compatible. You can upgrade from 0.9 to 0.10, but not the other way around.  

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