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I encountered a error whilst downloading Bitcoin-Qt on my Macbook version 10.6.8; it says "Failed to read block"
How do I fix this error without losing the bitcoins currently in my wallet?
Your assistance will be greatly appreciated.

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You say that you are 'downloading Bitcoin-Qt'. Are you using a browser to download Bitcoin-Qt, or are you using Bitcoin-Qt to download the blockchain? – Nick ODell Mar 28 '13 at 1:31
This question helped me with the same issue:… – rMX May 21 '13 at 8:08
-reindex worked for me! thanks for the tip! – user10226 Dec 5 '13 at 20:30

Start the client with the -reindex command-line option.

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If you backup the wallet.dat file, then you should be able to remove everything else, and then Bitcoin-Qt will redownload the block chain.

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This will work, but is overkill. – Pieter Wuille Jun 30 '13 at 22:36

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