Hi All
Im having this same problem and trying to download other versions of multibit and the same error is being returned.
i reverted back to all versions below 5.18 with zero success.
ive made backup of my wallet already as well just incase.
is there anything else i can try doing?
appreciate the help.
Can you remember if you put a password on your wallet? If you didn't try opening your wallet file in notepad and looking for "org.bitcoin.production" at the start of it. Newer wallets are in a format called protobuf, and newer wallets without a password definitely start with "org.bitcoin.production". I'm not sure what older format wallets start with.
If you have a newer format of wallet without a password the instructions in the quote below might work. Any hex editor should work as well as the one I linked to in the quote,
If you have an older format wallet (called serialised format) you can try adapting the instructions in the quote. I can't test them because I can't find a download for an old enough version of multibit. You search for "75 71 00 7e 00 11 00 00 00 41". If you find that series of bytes you probably have an older format wallet. In that case you can either try using the instructions at this link.
https://bitcointalksearch.org/topic/m.909038Alternatively you can search for each 20 in the file and copy the 32 bytes following every instance of 20. They might be private keys. If you remove any spaces and put them into the offline webpage described in the quote it will reject any false positives, and show any real private keys in a range of formats you can import into electrum.
Since version 0.4.0 multibit classic wallet files are in a format called Google protocol buffer format (protobuf). Open a file with a .wallet extension in a hex editor and look for the following sequence of bytes 08 01 12 20. The next 32 bytes after that should be your private key in hex format. After you get your private key in hex format you can convert it to a normal format using an offline copy of the bitaddress website.
I tested this on an unencrypted wallet (one with no password) in multibit version 0.5.1.6 and it worked for me.
This is the hex editor I used, although any other is probably sufficient.
http://www.wxhexeditor.org/home.phpThis is the bitaddress website. I advise you not to directly paste private keys into it.
https://www.bitaddress.org/Instead look for this link at the bottom of the page and use it to download a zipped copy you can run offline.
https://github.com/pointbiz/bitaddress.org/archive/v3.3.0.zipThis is my multibit wallet file opened in the hex editor with the bytes 08 01 12 20 that precede a private key highlighted.
This is the 32 bytes of a private key (in hex format) highlighted.
This is the 32 bytes of a private key (in hex format) copied directly from the hex editor into notepad.
This is the 32 bytes of a private key after removing the spaces in notepad.
This is the private key copied from notepad and pasted into an offline copy of the bitaddress wedsite. Click the view details button to get the private key converted to normal formats.
This is my multibit wallet's address 1F84fkbMng6dJpGZmtycRbUe72B7XSYbeT shown on the right hand side of bitaddress. Every raw private key can convert into two different bitcoin addresses, which is why there's two.
This is my multibit wallet's address 1F84fkbMng6dJpGZmtycRbUe72B7XSYbeT shown in multibit.
You can import your private key into the wallet of your choice to get control of yours coins back. Electrum's a good choice.
If you install electrum you can use these instructions to import your private keys from multibit into it.
http://docs.electrum.org/en/latest/faq.html#can-i-import-private-keys-from-other-bitcoin-clients