Are you sure it's a Bitcoin wallet.dat? Because the error message seems to say it's not.
Maybe you've played with testnet and it's from there, or, usually more probably it's from an altcoin, since most of them have their wallets based on various versions of Bitcoin's wallet.
Hi thankyou for the quick reply.
I've managed to use Bitcoin2john.py and the hash extracted is something like this: $bitcoin$64$
I always added the flag -walletcrosschain but Bitcoin Core seems to close abruptly when I attempt to restore the wallet.
I'm not 100% sure it's a Bitcoin wallet.dat but maybe the hash extraction confirms it is?