Bitcoin core wallet backup corrupted by an external tool Do you know if my wallet.dat which has become wallet.axx due to incorrect handling of an external program
(I do not know the name of the program, but it is used to encrypt Windows files)
has the possibility of reverting to initial format &quot;.dat&quot;
by myself ?
And above all without damaging the backup &quot;Core&quot; that it is ?
According to a random website coughed up by Google:

A file with the AXX file extension is an AxCrypt Encrypted file. AxCrypt is a file encryption program that scrambles (encrypts) a file to the point that it's unusable without first being decrypted with a specific password/passphrase.
When an AXX file is created, it's automatically assigned the exact same name as the unencrypted file but with the .AXX file extension appended to the end. For example, encrypting vacation.jpg results in a file called vacation.jpg.axx.
You can double-click an AXX file to open it with the AxCrypt software. However, note that if you're signed in to your AxCrypt account, double-clicking the AXX file will open the true file and not actually decrypt the AXX file.
Use the program's File &gt; Open Secured menu to open the AXX file but not actually decrypt it. To decrypt the AXX file requires that you either right-click it and choose AxCrypt &gt; Decrypt or use the File &gt; Stop Securing option