MultBit Change transaction bug

[heldertb]

Hello,

Every time I sent a transaction from my first address, a random amount of change (even not all what's left on the address) is sent to another address in my MultiBit wallet. Although multibit still shows a wrong balance on my first address (the balance it should be when the change is sent back to the same address). Even when I restart the blockchain on the first address, it still shows a wrong balance.
Why is Multibit not sending the change back to the same address the bitcoins came from?
Can someone help?

Thanks...

[shorena]

Yes, the other address should be your 2nd address or multibit has changed the way it handles change. Even if your balance is e.g. 2.56711 BTC on a single address most of the time this balance consists of several unspend outputs you can control. Each TX uses one or more inputs (former unspend outputs) to generate one or more new outputs. Each input used has to be spend entirely or the "rest" will go to the miners. Multibit does all this for you in the background and tries to find the best inputs for your TX.
Lets say you have 2.56711 BTC and received them as the following outputs from a TX

- (A) 2 BTC
- (B) 0.50011 BTC
- (C) 0.067 BTC

keep in mind that usually this is more complex.

Now if you want to spend 0.5 BTC multibit can use (A) or (B), but not (C) but in any case you will have change. If we use (B) as the input for your new TX you get an output of 0.5 to the address you wanted to send the BTC to, 0.0001 as a fee and another output 0.00001 as change to one address multibit controlls for you. 0.00001 is actually bad because it is so little, so multibit might prefer to use (A), not entirely sure about that.

I hope this helps you to understand this behaviour.

[heldertb]

Yes, the other address should be your 2nd address or multibit has changed the way it handles change. Even if your balance is e.g. 2.56711 BTC on a single address most of the time this balance consists of several unspend outputs you can control. Each TX uses one or more inputs (former unspend outputs) to generate one or more new outputs. Each input used has to be spend entirely or the "rest" will go to the miners. Multibit does all this for you in the background and tries to find the best inputs for your TX.
Lets say you have 2.56711 BTC and received them as the following outputs from a TX

- (A) 2 BTC
- (B) 0.50011 BTC
- (C) 0.067 BTC

keep in mind that usually this is more complex.

Now if you want to spend 0.5 BTC multibit can use (A) or (B), but not (C) but in any case you will have change. If we use (B) as the input for your new TX you get an output of 0.5 to the address you wanted to send the BTC to, 0.0001 as a fee and another output 0.00001 as change to one address multibit controlls for you. 0.00001 is actually bad because it is so little, so multibit might prefer to use (A), not entirely sure about that.

I hope this helps you to understand this behaviour.

I know how this system works. But I want the change back to the same address. Not to another address.
this is the transaction:
https://blockchain.info/tx-index/8de56c339ff1cab00e94fc2a5b032462112e5d913292bc90d7ec6544611e3baa

As you can see, I paid 0.01234862 BTC to the destination address. But the change from where it came from is sent to a completely different address... While Multibit doesn't show this in the transaction history of the address the BTC is sent from, meaning it still shows the old balance. So this is definitely a bug, and not just how Bitcoin transactions work

[shorena]

-snip-
I know how this system works. But I want the change back to the same address. Not to another address.
this is the transaction:
https://blockchain.info/tx-index/8de56c339ff1cab00e94fc2a5b032462112e5d913292bc90d7ec6544611e3baa

As you can see, I paid 0.01234862 BTC to the destination address. But the change from where it came from is sent to a completely different address... While Multibit doesn't show this in the transaction history of the address the BTC is sent from, meaning it still shows the old balance. So this is definitely a bug, and not just how Bitcoin transactions work

From the dev to someone complaining about what you want (change back to same address):

Hi BitHits,

The change address chosen in MultiBit is fairly simple. It uses the second address in the wallet, if it is available. If there is only one address it uses that.

You can send a transaction to yourself no problem - it is one of the release tests I always do - so it will not generate invalid transactions.

The wallets in MultiBit are random key addresses so creating a new one for change addresses requires people to reback up their wallets. There has been at least one case where a paper wallet user deleted a wallet with change addresses in and lost bitcoin. With the current wallet creating new keys is a user driven operation.

If you want more complex change control then of course you have the choice of other wallets - MultiBit endeavours to keep things simple for new users.

It should definitly show in the balance, but IIRC multibit does not show balances of individual addresses anyway.

[heldertb]

-snip-
I know how this system works. But I want the change back to the same address. Not to another address.
this is the transaction:
https://blockchain.info/tx-index/8de56c339ff1cab00e94fc2a5b032462112e5d913292bc90d7ec6544611e3baa

As you can see, I paid 0.01234862 BTC to the destination address. But the change from where it came from is sent to a completely different address... While Multibit doesn't show this in the transaction history of the address the BTC is sent from, meaning it still shows the old balance. So this is definitely a bug, and not just how Bitcoin transactions work

From the dev to someone complaining about what you want (change back to same address):

Hi BitHits,

The change address chosen in MultiBit is fairly simple. It uses the second address in the wallet, if it is available. If there is only one address it uses that.

You can send a transaction to yourself no problem - it is one of the release tests I always do - so it will not generate invalid transactions.

The wallets in MultiBit are random key addresses so creating a new one for change addresses requires people to reback up their wallets. There has been at least one case where a paper wallet user deleted a wallet with change addresses in and lost bitcoin. With the current wallet creating new keys is a user driven operation.

If you want more complex change control then of course you have the choice of other wallets - MultiBit endeavours to keep things simple for new users.

It should definitly show in the balance, but IIRC multibit does not show balances of individual addresses anyway.

Lol, this explains a lot...
Well that kinda sucks...
Any other good wallets out there? :p

[shorena]

-snip-

Lol, this explains a lot...
Well that kinda sucks...
Any other good wallets out there? :p

I like bitcoin-core with coin controll enabled because it allows you to select which inputs to use, where the change goes etc. Basically full control. It comes with the burden of a full blockchain though

But there are plenty wallets [1] I never tried, so maybe test a bit around.

[1] https://bitcoin.org/en/choose-your-wallet

[heldertb]

-snip-

Lol, this explains a lot...
Well that kinda sucks...
Any other good wallets out there? :p

I like bitcoin-core with coin controll enabled because it allows you to select which inputs to use, where the change goes etc. Basically full control. It comes with the burden of a full blockchain though

But there are plenty wallets [1] I never tried, so maybe test a bit around.

[1] https://bitcoin.org/en/choose-your-wallet

Yeah, Bitcoin-core is a pain because of the blockchain, oh well. I already started downloading it months ago, so why not continue with it.. :p

[shorena]

-snip-

Yeah, Bitcoin-core is a pain because of the blockchain, oh well. I already started downloading it months ago, so why not continue with it.. :p

If you make sure you get a good node to sync [1] its not that painfull.


[1] https://bitcointalk.org/index.php?topic=800893.0

[allgoodthings1]

My solution: Run three full nodes on a cheap VPS ($2/month each) (one would do fine, but I'm big on overkill) -- and use MultiBit for my software wallet.