Download NuBits blockchain (bootstrap)

Is there a link where I can download the zipped blockchain for Nubits?

Look for NuBootstrap012616.torrent on the repository download page.

Is there any guide on how to use that bootstrap file, looking at my .nu folder I got a database and a block folder, but the bootstrap is a single file, not sure if its a zip file that I need to unzip or I need to rename it as a specific file.

Here is an update to support you in downloading the large blockchain a bit faster. The bootstrap file mentioned above no longer works with client v3.x and above and the file itself was more than a year old anyway.

I’ve created a new torrent and have a few people seeding it so hopefully it speeds up the process significantly. You can find the torrent in the Nu repository. Look for the file NuChain9-Apr-17.torrent.

You will need a Torrent client like uTorrent pre-installed to download the blockchain files.

Once you have completed and downloaded the two files for 100% please follow the following instructions:

  1. Start client and let it go for a minute or so to ensure your folder structure and the wallet has been created.
  2. Stop client
  3. Copy both files into the .nu folder (for Windows under %appdata)
  4. Start client again

It will now be synchronising only the last few weeks/months instead of the entire blockchain from scratch.
Please drop a line here if you get stuck somewhere in the process.

It would also be much appreciated if you would be able to seed it for a while so others can also enjoy a fast download.


After following the instuctions, I got:

EXCEPTION: 11DbException
Db::open: Operation not permitted
D:\Nu\nu.exe in Runaway exception

EnvShutdown exception: DbEnv::close: Invalid argument (22)

Should I get rid of the “__db.00x” files ?

Was it a completely clean .nu data directory that you copied the bootstrap files into? I think it could confuse the client if there are existing files already in the folder. I’d recommend backing up your existing folder to a different location and then starting the Nu client briefly to create a fresh one.

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That is my experience too. Just keep your wallet.dat if there are any coins in it, clear everything else. Start client and let it create all basic files. Stop it after 1 minute or so and replace the blockchain files with the ones you downloaded.
Done it multiple times, no problem.

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Unfortunately it does not work here.
No doubt that Polo does not want to face the trouble of upgrading…:frowning:

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I’m not having any luck either.

If I paste in the downloaded blockchain files NU won’t start.

If I swap the files back in again, it starts fine. I’m not sure what’s causing these blockchain files to not work on some installations (including mine).

With an new wallet or an existing wallet? I can’t reproduce it. Is this with Windows 7 or 10 or?
Just make sure you start without anything in the .nu folder, let the client run and create all files, stop the client (important) and only then swap the blockchain files. Start the client. Would be interesting to see what kind of error is in the debug.log.

It’s windows 10 64 bit, new wallet.

I closed Nu, deleted the whole Nu folder (there’s no ‘.nu’ folder - just ‘nu’, so not sure if that’s normal?), restarted Nu and closed once folder & files were there, then closed Nu again, replaced the files, then this error occurred when restarting:

A fatal error occured. Nu can no longer continue safely and will quit.

EXCEPTION: 22DbRunRecoveryException DbEnv::open: DB_RUNRECOVERY: Fatal error, run database recovery
C:\Users\David\Desktop\CryptoCurrency\nu-5.0.1-win-gitian\64\nu.exe in Runaway exception

The last part of the log file had this:

ProcessBlock: ACCEPTED
ThreadMessageHandler exiting
ThreadStakeMinter exiting, 0 threads remaining
ThreadUpdateFromDataFeed exited
UPNP_DeletePortMapping() returned : 0
ThreadMapPort exiting
addr.dat refcount=0
addr.dat checkpoint
addr.dat detach
addr.dat closed
blkindex.dat refcount=0
blkindex.dat checkpoint
blkindex.dat detach
blkindex.dat closed
Nu exiting

select() for connection failed: 10038

Any hints would be appreciated, but I’m ok to leave it syncing for now, and hopefully it’ll get all the way!

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i am having the same kind of error.
syncing from scratch now.
i noticed you need at least 8gb of ram.

It is about 2.5Gb for client so 4Gb can be tight on Windows if you are running other stuff.

Will do some testing with Windows. I could create a specific Windows set of blockchain files if that is a solution.


I’m really puzzled by this. Just used the two blockchain files published and copied them into an existing but old Nu folder in %appdata on a Windows 7 with 8Gb. Not deleting any other file or folder. It took the Nu 5.01 client about 25 minutes to ‘process’ and start but it did start and works. No errors and almost synced, just syncing the last few weeks. Maybe it is a W10 specific issue or is the wallet.dat corrupt? Would it work with a new wallet.dat? Any suggestions are welcome.

It will, it just takes a few days. Once synced I would recommend to make your own copy of the two files, so you can always fall back when something goes wrong or you need to run another client and you need to sync again.

Edit: It just occurred to me that you could be to fast after stopping the client with replacing the files. Make sure you wait until the client has stopped and removed all the temporary files. Or just check the task manager to ensure Nu is not running. It sometimes takes a while to stop Nu. Only copy the blockchain files if you are sure it stopped. That may have caused the corrupted files. Best to clear out all files (except wallet.dat if you have coins) and try again.


Just to confirm, I made sure temp files had been cleared, and checked task manager for Nu, and did this all multiple times with the same result. New wallets each time - completely deleted existing Nu folder.

I’ll make a backup of my synced blockchain once it’s done.

Edit: after synchronising, most of my balance was missing. Thankfully I had the same wallet accessible from my Coinomi wallet, so I transferred the balance from this to a new wallet. Strange behaviour all around!

You can run checkwallet / repairwallet in the console under debug window. That usually fixes the balance issue. Make always sure you make a backup of your wallet first. Just in case.

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Does this work on OSX?

I can confirm the latest blockchain files working with macOS wallet.

Nu blockchain 2017–09–17


I am over a week trying to download the chain by sync, raw file and torrent. Sync is too slow, RAW doesn’t work any more I found out in forum after wasting hours and now the torrent doesn’t work either no matter what I try from the above posts. Getting the a database fails to open exception when I copy over the *.dats.

Would someone kindly upload a current torrent of the chain and advise how the heck I get this thing to work? Linux client 5.3. Thanks

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