Topic: Electrum 1.8.1 Stuck on Block 251526 (Read 10507 times)

Try a different server and make sure you included enough fees.

This appears to be happening again. I cant send. TX rejected code -22.

I went to bed and when I looked again that one finally was OK.  But I just sent 1 BTC somewhere else 20 minutes ago and it's not showing up in the chain yet.  A few other transactions were pretty slow yesterday too, but I can't get a fix on if it was electrum or the sender, or both.

As for todays transaction, I'll PM you the ID. 


Well, as I was writing that, there were 2 confirmations  I opened and closed the client during that time.  Now I'm just wondering about the delays in general, previously, transactions would generally show up in the blockchain almost immediately, although unconfirmed.  Been slower since the stuck block it seems.  I'll keep monitoring it.

Do you have the transactiond id?

I was wondering what was going on.  I'm connected to electrum.be now, but still not seeing a sent transaction in the blockchain, even unconfirmed.  Transaction shows in the electrum client as pending since about an hour ago.   I'm at 252,151 blocks right now.

That was a really helpful post as I experienced this problem today when attempting to send out some BTC. The strange thing was on my first attempt the funds actually arrived, but didn't show up on my transaction history - and other attempts to send failed, as per above comments. Changing the server fixed the problem - so thanks!

There appears to be a bug (regression) with servers not connected to IRC and Electrum > 1.7 . The client only shows the one server you're connected to, which is a problem if this is a server still stuck on 251526. It should show a list of built in servers.

To resolve this you manually have to enter one of the servers like:

electrum.be SSL 50002
electrum.no-ip.org SSL 50002
electrum.pdmc.net SSL 50002

My Abe got struck at 251526. Updating of Abe from github resolved the issue and the scanning went ahead

Thx for posting this!
How is "second bug" meant? How do you read the patch? It's still the same issue? I guess I'm missing something?


abe was fairly quick:

commit 2b721e1df441396d04cea8b34ebe7b77488ddf52
Author: John Tobey
Date:   Mon Aug 12 13:44:39 2013 -0400

    Merge bitcointools upstream changes and update callers.


If I read the timestamp right that's less than 2 hours after the fix got included in the blockchain. That's rather quick and the change fixes other things with it. Too quick, but maybe he got a PM around the time it was accepted in the mempool at Eligius ?

Note that I mentioned double-byte opcodes a few weeks ago on the forums; there's lots of people who know about this stuff and could have made that transaction.

I should also point out that the transaction appears to not only include a patch to fix Electrum, but at the same time also triggers the bug it patches. I think what happens is that the OP_INVALIDOPCODE triggers the broken double-wide code to advance a byte, ORing that byte with OP_INVALIDOPCODE << 8. Unfortunately that character is a PUSHDATA, which means that Electrum now processes the data as though it were opcodes. The next byte is 0x4e, or OP_PUSHDATA4, followed by the length of the data to be pushed, 0xffffffff=2^32 bytes. Of course there aren't 4GiB of data in the script, so it fails and Electrum gets stuck.

I think the OP_IF/OP_ENDIF was meant so that the transaction could be spent, but whomever did so forgot that PUSHDATA's > 520 bytes make a transaction invalid. Thus unless we change that limit - a hard-fork - the 15mBTC will be unspendable forever. (invalid opcodes are legal in an un-executed IF/ELSE/ENDIF branch, but oversized pushdata's are not)

I rather doubt that Satoshi would have made that mistake. 


That's just a reference to the previous commit ID the patch is meant to apply too. If you save that patch to a file you can apply it with git am patch.diff, it was probably created with git format-patch from the looks of it.

I think he did include a git signature:

a3a61fef43309b9fb23225df7910b03afc5465b9

So, is this him? Anyone can write something with a header saying from "From: Satoshi Nakamoto <[email protected]>", but I can't picture someone searching through the entire commits history of bitcoin to find the relevant commit that matches what he's talking about (f1e1fb4bdef878c8fc1564fa418d44e7541a7e83, which does indeed exist and it is a commit by Satoshi). Satoshi, if you are reading this, add your digital signature next time, even if you are trying to be extra cautious it can't possibly do much harm.

Can't send anything from my electrum wallet, tried using electrum.be and electrum.no-ip.org, no joy. Keep seeing that error -22 message. Any ideas what I can do? thanks

EDIT: All sorted now 

I can write an email with "From: Satoshi Nakamoto <[email protected]>" in the header too, and embed it in the blockchain.

What would you like your letter from Satoshi to say?

What's this?


More specifically:


It's been several hours since this was posted and I don't see the entire net screaming "Satoshi is alive!!!" all around, so I guess I must be the only one drawing the wrong conclusion from those two lines. Someone willing to state that obvious thing that I fail to see?

thank you guys for the quick fix!

You can also use your electrum passphrase at carbon wallet. http://carbonwallet.com/

Transaction ID: 77822fd6663c665104119cb7635352756dfc50da76a92d417ec1a12c518fad69 contains the patch for the second bug:


I guess this was code monkey-copied from abe?  I suppose someone should go fix that too.

Thanks for the fast solution 

Thanks. Switched there, and everything's working!

electrum.stepkrav.pw up n running. 

I did some simple tests with tx from block 251526 and they are indexed just fine on a crashed server after the fix is applied. Unless the server throws "LevelDBError: Corruption" on startup as has been reported but might be unrelated it's sufficient to stop the server, pull git head and start the server.

Servers electrum.be and electrum.no-ip.org are fixed and up to date.

Thanks to DigitalHermit for the fix, which is pushed to electrum-server on github (https://github.com/spesmilo/electrum-server/). We're urging all server operators to apply the fix. If you want to make sure your server database has a correct block 251526 indexed please re-index from a backup (i.e. from the foundry linked above). We're still researching how unpatched servers handled 251526...

You can create a wallet at blockchain.info and import the private keys from your electrum wallet if you need access to your funds immediately. Otherwise, sadly yes you will have to wait for a fix.

Looks like we got caught off-guard on a Sunday. Rest assured we're working on getting this fixed asap. The coins are safe. Just seeing new tx and spending coins is not possible at this time.

To Server operators:

The dumps at http://electrum-foundry.no-ip.org/leveldb-dump/?C=M;O=D  generated this morning around midnight have a clean, uncorrupted database to use once we have a fix to get past offending block 251526.
See also http://electrum-foundry.no-ip.org/

I didn't know that electrum is that awesome!

It takes some hours until I finished the download of the blockchain.

I guess with some code wizardy you can export the private keys to bitcoind or multibit.

Export your private key to another wallet client.

Is it possible to use the bitcoins at this moment? How long do you think does it take until this issues are fixxed?

Checking in as this was starting to effect me and was wondering what's going on. Thanks OP.

I am just surprised I hadn't read more people in the same situation.

Apparently there is an issue in script_GetOp(bytes) (deserialize.py) for this particular block that makes the electrum server code read off the end of the byte array when trying to read the operation. I don't know if this is an issue with the format of this specific block or with the python code. If it's an issue with the block format I'm surprised it has gone undetected this long - apparently bitcoind code permitted/accepted this block.

Thank you DigitalHermit, thought I would ask in here once I discovered a problem.
Hopefully it can be resolved quickly.

It is not your wallet that is the problem; The problem is on the Electrum Server(s)... this will need to be fixed in order to make Electrum clients functional again.

The exception we are seeing server-side is:

As per the title, no matter what server I reconnect to, it will not go past block 251526

I have tried all the servers
Deleted the contents of /appdata/Roaming/Electrum
Recovered the wallet using my seed & resynced

All to no avail, It will not let me send my balance out of the wallet giving the error -22

Any help is appreciated.