If you restore an old wallet.dat into a new node installation, the software will need to "rescan" the blockchain. It must check every block in history to see if any transactions were sent to the addresses in your wallet file. This can take hours, but it is a necessary part of syncing your history.
While it functions as a single file on the hard drive, wallet.dat is actually a database containing several distinct types of records: Bitcoin Core Wallet.dat
Scenario: Your computer died, but you have your wallet_backup.dat on a USB stick. If you restore an old wallet
Step-by-step recovery:
The Long Wait: Bitcoin Core must rescan the blockchain to find all transactions belonging to your restored keys. This can take hours. You will see a progress bar reading "Rescanning..." at the bottom of the window. The Long Wait: Bitcoin Core must rescan the
Pro Tip: If you only have a backup from 2017 and haven't used the wallet since, you do not need to download the full blockchain to check your balance. Use a tool like pywallet or import the private keys into a lightweight wallet like Electrum.