Import old paper backup (WIF private key) into modern Bitcoin-QT

Question

When trying to import a WIF private key into Bitcoin-QT i get this error:

Only legacy wallets are supported by this command (code -4)

How can one import a private key on a non-legacy wallet?

Answer 1

I don't know how to perform this on the GUI, but in order to import a WIF private key on a modern Bitcoin Core you have to use a descriptor. In order to recover from a backup, you most likely want to use the combo() descriptor.

Here is an example with an example WIF private key: cSWVo8YMehg6STxqw6xGgmMJE6Ac6RCJ7owcrBZRAT7QANtyAAEj (it's a testnet-encoded WIF private key on purpose, yours will be different). There is most likely a similar flow on the graphical interface, but failing that you can always use the command line (or the command input on the GUI).

First craft a combo descriptor from this private key and get its checksum:

getdescriptorinfo 'combo(cSWVo8YMehg6STxqw6xGgmMJE6Ac6RCJ7owcrBZRAT7QANtyAAEj)'

We get:

{
  "descriptor": "combo(023ad6336ae257527ff59ec4356fa5d2ac33fff5e04be9e5958dfed9b0100b7948)#mv9rgx7y",
  "checksum": "9zedq5ns",
  "isrange": false,
  "issolvable": true,
  "hasprivatekeys": true
}

You can now import this descriptor using the importdescriptors command:

importdescriptors '[{"desc":"combo(cSWVo8YMehg6STxqw6xGgmMJE6Ac6RCJ7owcrBZRAT7QANtyAAEj)#9zedq5ns","timestamp":"now"}]'

Finally rescan the blockchain from a point before which you are certain to not have received coins. To rescan the whole chain from the genesis block do not provide any parameter:

rescanblockchain

Answer 2

importprivkey only works on legacy wallets, so you need create a legacy wallet and then import the private key succ.

1. create a new wallet with descriptor wallet unchecked.
2. go to console and importprivkey.