Bitcoin Forum

Hi i got a old saved bitcoin wallet on a memory card it is from 2014 i think but the saved files are in key format not in .dat what can i do to make it work ?  :)

Since it's a .key then there is a high chance this is a multibit wallet file!
Download both multibit classic and HD and see if any of them opens it. If the file is encrypted, then you will need to remember the password you used to encrypt it with.

I can't seem to find any legit multibit out there except their GitHub but it seems they don't have multibit classic installer.

I think you can follow the guide from this link below
- https://github.com/Multibit-Legacy/read-multibit-wallet-file/tree/c4956f1c5a1ecb2df7a5612c8d9ea04388cdde0f#importing-to-electrum

But the only problem I don't know if it will also work on .key file to extract/export private keys and import them to Electrum.
Anyway, just try and let us know so that we can find another way to help you.

thank you it was multi bit that was used is multi bit wallet bad ? is it a good idea to move it to a bitcoin core wallet ?

It's not bad, it's simply not maintained by the developers anymore, you won't be able to make any use of it at this point: https://bitcointalk.org/index.php?topic=2293714.0

Bitcoin core is good, but if you want to stick with lightweight wallets then Electrum would be a better choice.

Can i use multi bit to sent the money to a new bitcoin core wallet ? :)

No, you won't be able to send the funds as the wallet is no longer functional. If you want to move the funds to bitcoin core, you will have to first export the private keys as the link above explains, and then import them by following these steps[1].

[1] https://bitcoin.stackexchange.com/questions/5941/how-do-i-import-a-private-key-into-bitcoin-core

0. Especially if there is more money in that wallet, make sure your computer is malware free. If someone else gets access to your private keys you'll lose your coins.
1. Make a backup copy of the .key file.
2. Open the .key file with notepad and look if the line or lines that don't start with # are something like

5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF 2014-01-01T18:46:20Z

Where the first part is 52 chars long, then there's a space and a date.
If you have this format, you can easily import. The 52 char strings are the private keys and you can ignore the date.

If it's not, then it's password protected and you have to remember the password, open the file in Multibit then save it without password.
If it's not password protected, you have the private key (or keys, if there are multiple lines).

You can import them easily into Electrum. (make sure you download it from electrum.org and verify it before installing! https://bitcoinelectrum.com/how-to-verify-your-electrum-download/)
3. In the "Create new wallet" step you choose "import bitcoin addresses or private keys"
4. At next step copy/paste the long strings (private key, no date) into Electrum and prepend them with p2pkh: so it'll look like
p2pkh:5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF
(this is an example, make sure you use your own private keys)

If there are more private keys in the .key file, do this for all, one private key per line.

Next.next... until you finish all the steps and you are good.