Warning:
Text: curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when safe_mode is enabled or an open_basedir is set
File: /home/nextmg/domains/bitcoin-and-blockchain.education/public_html/libs/magenet_class.php
Line: 261

Warning:
Text: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/nextmg/domains/bitcoin-and-blockchain.education/public_html/code/utils.php:439)
File: /home/nextmg/domains/bitcoin-and-blockchain.education/public_html/code/items.php
Line: 2

Warning:
Text: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/nextmg/domains/bitcoin-and-blockchain.education/public_html/code/utils.php:439)
File: /home/nextmg/domains/bitcoin-and-blockchain.education/public_html/code/items.php
Line: 2

Bitcoin wallet format :: Bitcoin and Blockchain
Bitcoin Vulnerability: The Parallel With Social Security And

Bitcoin wallet format

Bitcoin Wallet / December 15, 2018

If you load the wallet file in a modern Bitcoin Core version, you can use the dumpwallet command (to create an unencrypted dump of the keys), and the importwallet command in a fresh instance with a new empty wallet.dat of the dump. You will need to rescan afterwards, though, which may take a while.

Make sure to wipe the dump file afterwards.

Using db dump/load

One way is to use the following command on a Linux install with db4.8-util installed: db4.8_dump wallet.dat | db4.8_load wallet.dat.new

This will create a new wallet.dat.new file, with the same records as the wallet.dat file, but without any old potentially never-overwritten data.

db4.8-util may be hard to install these days, as most distros stopped distributing db4.8, in favor of 5.1 and later. Bitcoin Core however still uses 4.8 for compatibility reasons. You can use db5.1-util as well, but that means that you'll need a Bitcoin Core version compiled with db5.1 support afterwards to use the newly constructed wallet file.

Source: bitcoin.stackexchange.com