15 votes
Accepted

Check status of daemon?

I found the easiest way to do this (version 0.12) is to issue the command (not case sensitive): bitcoin-cli getblockchaininfo Then, compare the blocks received field, to the headers field. The ...
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14 votes

Creating my own bootstrap.dat?

Bitcoin Core contains a tool to do this properly (filtering out any orphan blocks, putting everything in the correct order — which will work a lot better than just concatenating the block files. It's ...
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14 votes

How to know if bitcoind synced?

You can compare the block count from Blockexplorer with your local block count. Something like this: $ wget -q -O- https://blockchain.info/q/getblockcount; echo 359721 $ bitcoin-cli -conf=/u0/bitcoin/...
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13 votes
Accepted

Blockchain synchronization is painfully slow / Best way to download blockchain

What usually takes time is the validation of the transactions in the blockchain, not downloading it. Bitcoin Core implements a fully validating node, which does not trust any of the information other ...
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11 votes
Accepted

Safely interrupt -reindex?

Yes. You can just stop bitcoind (using bitcoin-cli stop, or just killing it with SIGINT). Next time invoke it without -reindex, and it will continue from where it left off. If you do pass -reindex ...
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11 votes
Accepted

Sync with bitcoin-qt very slow (0,01%)

Bitcoin Core sync very slow Bitcoin Core is capable of full sync in a relatively short period of time depending mainly on the hardware. Most of the work done is not actually downloading the blocks, ...
11 votes
Accepted

Bitcoin Core - Go back to a specific block?

You can't delete the block data themselves, but you can reset the blockchain state to a specific block by using the invalidateblock command. This command will mark a specific block and its descendants ...
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  • 60.4k
11 votes
Accepted

Is there a way to only sync up to a certain block?

bitcoind supports the argument -stopatheight, which takes the number of blocks to download before halting.
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  • 15k
10 votes
Accepted

What does "Activating Best Chain" mean?

Bitcoin Core maintains two databases: The block index The chain state (or UTXO set) The first one just contains a list of all blocks we know about, valid and invalid. It contains all forks we have ...
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10 votes

Check status of daemon?

You can also just tail the debug.log file in a new terminal window while bitcoind is running. It shows current block height i.e. height=181888 and percentage of download complete i.e. progress=68....
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10 votes
Accepted

Why is it bad to download the full chain from a third party with Bitcoin Core?

No, the chainstate is the nodes view of correctness. It would take many hours or days to re-verify the whole chain on most hardware, so an assumption is made that the state stored at the previous ...
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  • 15k
9 votes

How to know if bitcoind synced?

bitcoind logs the current sync status to its debug.log file: $ tailf ~/.bitcoin/debug.log 2017-05-26 03:49:16 UpdateTip: new best=0000000000000001e0b7c8cffb8e7fa23909b8728913663decfaebffe24ca689 ...
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  • 191
9 votes
Accepted

Bitcoin core wallet transactions and synchronisation

With Bitcoin Core you'll run a full node. So, for every transaction someone does to your business, your Bitcoin Core wallet need to be synchronized with the complete blockchain.
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  • 306
9 votes
Accepted

Does assumevalid lower the security of Bitcoin?

which, as I understand it, makes some data (until 2017?) real without verification. You understand incorrectly. Firstly, the assumevalid blocks is updated at every major release, so it is at most a ...
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  • 60.4k
8 votes

Can I retrieve my bitcoins from years ago that I never received?

If you still have the wallet.dat file and your password you can access your bitcoins. You do not have to use Bitcoin-Qt 7 and it does not matter if your wallet ever synced before. If the sender sent ...
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8 votes
Accepted

Faking blockchain data in bitcoin-core

Let's say I found a tarball with blockchain data files which I load to my datadir and start my Bitcoin Core client, what sort of attacks am I vulnerable to? Could the files contain fake balances? It ...
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8 votes
Accepted

How many peers do you need to securely synchronize with the blockchain?

One! Your full node will check every transaction and every block for validity while synchronizing. You therefore can be sure that whatever blockchain data your node accepts follows all rules of ...
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  • 62.3k
7 votes

I can't find my bitcoin address and my bitcoin core is out of sync by 3 years

Go to the top left, click File then receiving or sending addresses. There, you can create new adresses and look at your current addresses.
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7 votes

My Bitcoin Qt is behind 7 years and 32 weeks

If you shut down your PC and then restart, the Bitcoin sync will pick up where it left off. The latest transaction your Bitcoin currently knows about is 7 years old, but it won't take 7 years to ...
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  • 3,401
7 votes
Accepted

Can bitcoin core verify a third party blockchain download?

If you give Bitcoin Core a fully populated data directory, it will use it without any validation. However, if you only give it the blocks/ subdirectory, it will fully validate it to recreate the ...
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6 votes
Accepted

What can I do when the blockchain synchronization is stuck at a specific block?

I had this happen to me once. It was apparently caused by an incompatible peer node. Delete $HOME/.bitcoin/peers.dat Restart bitcoind Afterwards, new compatible peers will be found, and hopefully, ...
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6 votes
Accepted

What does UpdateTip mean?

In an earlier Version of bitcoin-qt the line was the following: SetBestChain: new best=0000000000000419f719 height=212580 work=666804971104474944731 From: https://bitcointalk.org/index.php?topic=...
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6 votes
Accepted

When I'm downloading the blockchain for the first time, from whom am I downloading it from?

Blocks are downloaded from other nodes in Bitcoin's P2P network using a custom wire protocol. For the initial synch you can imagine it as a torrent with 5000 seeders, though the Bitcoin P2P protocol ...
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  • 15k
6 votes
Accepted

Has the bitcoin network ever been "down"?

A bitcoin node could be down or (extremely rarely as you say) all its peers could be down... but the bitcoin network could not be considered down; you could still synchronize by connecting to ...
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  • 2,204
6 votes
Accepted

How to check if my node is fully sync'ed

Calling getblockchaininfo is your best bet. It includes a field called verificationprogress, which is an estimate of how much of the chain you have validated. Alternatively, compare headers to ...
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  • 8,724
6 votes

Check status of daemon?

run bitcoind getinfo, compare the block count to the current block height of several major block explorers such as: https://blockchain.info/ https://www.blocktrail.com/BTC https://blockexplorer.com/...
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6 votes
Accepted

what is the "Banlist" (Bitcoin Core)

It is a blacklist of erroneous nodes' IP addresses which has accrued a certain amount of banscore due to "misbehaviour". To check what sort of erroneous behaviour is considered "misbehaving", you can ...
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  • 2,378
6 votes
Accepted

Is -blocknotify triggered during catch-up?

Yes, this is by design. The notify action is run in the function BlockNotifyCallback (init.cpp), and you can see: static void BlockNotifyCallback(bool initialSync, const CBlockIndex *pBlockIndex) { ...
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6 votes
Accepted

Is Bitcoin Core storage compatible across different machine architecture?

The database format is supposed to be compatible across architectures.
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6 votes

Does running a pruned node support the syncing of other nodes in the network?

does such a node support the syncing of other nodes in the network? Nodes that are pruned unset the NODE_NETWORK flag, which means that they don't advertise themselves as a potential source for block ...
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  • 15k

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