I had same question, when wallet said "IMPORTANT: Any previous backups you have made of your wallet file should be replaced with the newly generated, encrypted wallet file. For security reasons, previous backups of the unencrypted wallet file will become useless as soon as you start using the new, encrypted wallet."
wallet.dat before encryt = encrypted wallet.dat which spent nothing after encryt
I think meaning of "as soon as you start using the new, encrypted wallet" is "as soon as you send money using the new, encrypted wallet"
from reddit.
http://www.reddit.com/r/dogecoin/comments/1x7vhp/please_explain_something_important_to_me/
ninja shibe
Yes you are right but I would add this:
When you set an encryption key for your wallet, all unused keys in it get marked as used, so they won't be handed out to satisfy requests for new addresses. This is to keep you from getting money sent to potentially unsafe keys. However, the keys are not marked invalid or discarded, so if you do manage to get one (using pywallet or db_dump or something), you can still use money sent to it.
Now, with all of the keys marked as used, your node needs to generate a bunch of new keys for the keypool, so that it can give you addresses without asking for the encryption key again*. This means that your wallet now has a bunch of keys in it that are not in the backup you made before encrypting. If you ask for a new key, and then restore from your backup, any money sent to that key will be lost and gone forever. So, right about now is a very good time to try to scare you into making a new backup.
The reason the message says that your wallet won't work any more is because people don't want to read a detailed essay on wallet key and backup management. The message just needs to convince people to make new backups, not necessarily go into all of the gory details about how and why.
If you can think of a concise message (that is also easily translatable) that is likely to get people to make new backups, without technically being a lie, please suggest one.