<p>When I've had this happen it's been because of a non-clean shutdown. Something about the disk state ends up being inconsistent and this (understandably) results in the system wanting to verify all the information it has on disk.</p>

CC BY-SA 3.0
2013-04-17T15:12:35.183Z
2013-04-17T15:12:35.183Z
David Ogren
<p>Bitcoin QT finished syncing this weekend after d/l for Windows 7 on Thursday.</p>

<p>Today, probably 2nd or 3rd time running it, an error came up right away that index could not be found.</p>

<p>What would cause this to happen, and why would it have to reindex all the blocks on disk?</p>

<p>Thanks, Mike</p>

CC BY-SA 3.0
2013-04-16T22:19:51.490Z
Did you recently do a non-clean shutdown? (Crash, power loss, etc)
Tom van der Woerdt
CC BY-SA 3.0
2013-04-17T01:15:40.287Z
Running a rescan might help: http://bitcoin.stackexchange.com/a/7734/516
Highly Irregular
CC BY-SA 3.0
2013-06-16T22:56:03.523Z
-rescan checks for missing wallet transactions. The error here is because a database sanity check at startup fails, where the wallet isn't even touched yet.
Pieter Wuille
<blockchain><bitcoin-core><windows>
Block data error, reindexing blocks
Mike
# Block data error, reindexing blocks

(Asked by: username_0 on 2013-04-16)

Bitcoin QT finished syncing this weekend after d/l for Windows 7 on Thursday.

Today, probably 2nd or 3rd time running it, an error came up right away that index could not be found.

What would cause this to happen, and why would it have to reindex all the blocks on disk?

Thanks, username_0

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

> **Comments:**
> **username_1**: Did you recently do a non-clean shutdown? (Crash, power loss, etc)  
> **username_2**: Running a rescan might help: http://bitcoin.stackexchange.com/a/7734/516  
> **username_3**: -rescan checks for missing wallet transactions. The error here is because a database sanity check at startup fails, where the wallet isn't even touched yet.  

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## 1 answers

### Answer by username_4 on 2013-04-17. Score: 2

When I've had this happen it's been because of a non-clean shutdown. Something about the disk state ends up being inconsistent and this (understandably) results in the system wanting to verify all the information it has on disk.


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