Newly installed Bitcoin qt does not see previously downloaded blocks

[RHBTC]

I have a 64 bit Win 7 laptop, use Seagate portable drive (drive E ) to run Bitcoin full node. No funds were ever stored in the core wallet.
Had previously downloaded Bitcoin core version 14, then upgraded to 14.1 and BIP 148. All worked fine, but I messed something up. The latest client crashed every time I tried to start it.

Uninstalled everything, deleted all files, just saved the blocks file.

Reinstalled the core 14.1 back on drive E, but when it starts it does not see the downloaded blocks on drive E, but rather starts loading the blockchain anew.

How can I ensure the newly installed client uses the downloaded blockchain? I have no coding software background, "for dummies" instructions would very much appreciated.

[achow101]

Is the datadir correct? If you go to Help > Debug Window, it will tell you what your datadir is. If it is not correct, go to the folder where Bitcoin Core is installed and find the bitcoin-qt.exe file. Then open a command prompt window. Then type

Code:

bitcoin-qt.exe -choosedatadir

and hit enter. This will start Bitcoin Core with the prompt to choose your datadir and choose wherever you want Bitcoin Core's data to be stored. You can then stop Bitcoin Core and start it normally, it will use the datadir you selected.

Also, you will need to reindex the blockchain. This is because you only copied the blocks folder and not the chainstate. The chainstate folder contains all of the databases, and without it, the databases will need to be rebuilt. The reindexing process looks like it is resyncing, but it really is not. It only looks like it is resyncing because it has to read through all of the blocks and validate all of them.

[RHBTC]

Also, you will need to reindex the blockchain. This is because you only copied the blocks folder and not the chainstate. The chainstate folder contains all of the databases, and without it, the databases will need to be rebuilt. The reindexing process looks like it is resyncing, but it really is not. It only looks like it is resyncing because it has to read through all of the blocks and validate all of them.

I believe this is reindexing that I have mistaken for the resyncing. Your detailed help is much appreciated!

[RHBTC]

Hi achow101,
my re-indexing went fine until about a year of blocks left. The "fatal error..." message stated popping up and the client shuts down. Here is the log from the debug:


Corruption: block checksum mismatch
2017-06-23 01:03:39 *** System error while flushing: Database corrupted
2017-06-23 01:31:39 Failed to connect best blockFailed to open mempool file from disk. Continuing anyway.
2017-06-23 01:31:39 socket sending timeout: 1689s
2017-06-23 01:31:39 socket sending timeout: 1717s
2017-06-23 01:31:39 socket sending timeout: 1754s
2017-06-23 01:31:39 socket sending timeout: 1689s
2017-06-23 01:31:39 socket sending timeout: 1686s
2017-06-23 01:31:39 socket sending timeout: 1686s
2017-06-23 01:31:39 socket sending timeout: 1740s
2017-06-23 01:31:39 socket sending timeout: 1691s
2017-06-23 01:31:39 socket sending timeout: 1703s
2017-06-23 01:31:39 socket sending timeout: 1686s
2017-06-23 01:31:39 receive version message: /bitcoin-seeder:0.01/: version 60000, blocks=350000, us=70.31.40.162:8333, peer=32
2017-06-23 01:31:39 receive version message: /bitnodes.21.co:0.1/: version 70015, blocks=472465, us=70.31.40.162:8333, peer=33
2017-06-23 01:31:39 tor: Thread interrupt
2017-06-23 01:31:39 opencon thread exit
2017-06-23 01:31:39 net thread exit
2017-06-23 01:31:39 torcontrol thread exit
2017-06-23 01:31:39 addcon thread exit
2017-06-23 01:31:39 scheduler thread interrupt
2017-06-23 01:31:39 Shutdown: In progress...
2017-06-23 01:31:39 msghand thread exit
2017-06-23 01:31:39 Corruption: block checksum mismatch
2017-06-23 01:31:39 *** System error while flushing: Database corrupted
2017-06-23 01:31:51 Shutdown: done
2017-06-23 01:32:18

Any suggestions? Thanks again.

[achow101]

Hi achow101,
my re-indexing went fine until about a year of blocks left. The "fatal error..." message stated popping up and the client shuts down. Here is the log from the debug:


Corruption: block checksum mismatch
2017-06-23 01:03:39 *** System error while flushing: Database corrupted
2017-06-23 01:31:39 Failed to connect best blockFailed to open mempool file from disk. Continuing anyway.

This usually means that you have a corrupted block on disk. The only way to fix that would be to delete the entire blockchain and let it fully sync from scratch.

[RHBTC]

Thanks again.