Historically, Bitcoin Core relied on Berkeley DB (specifically version 4.8) to manage the transactional key-value store of wallet.dat . This version is strictly required for backward compatibility; opening a legacy BDB file with a newer database version can permanently alter the file structure and prevent older software from reading it.
If you are managing this file, here is what you need to know to keep your funds safe: 1. Where to find it Bitcoin Core Wallet.dat
The first time you install and launch Bitcoin Core, it automatically creates a default Wallet.dat file in its data directory. It generates a keypool of 100 addresses. You will see a blank transaction list and a single receiving address. Bitcoin Core Wallet.dat