0.12.1 was not released 9 months ago. It's much newer than that.
You're right. Going through the debug.log, I see I was probably on version 10.2.
The log only goes back so far. According to log I was on version 0.12.1 much later.
Are you sure you are using the correct wallet file? Is the correct file in the correct data directory?
Using Windows for the moment, I keep the wallet file in C:\Users\[USERNAME]\AppData\Roaming\Bitcoin.
That's the default directory.
I've been switching between different wallet files and restarting bitcoin when I do that.
I have not kept a repository on the wallet files, something I realize in hindsight I should have done.
No, you're wrong. Bitcoin Core does pregenerate 100 addresses and those are in fact stored in the wallet file.
OK, that's good to hear. As long as it's my mistake I might figure it out.
[later]
All right!
I got it back!
Most helpful was achow101. Please PM me a bitcoin address for your reward. It's too much for so little work, but I stand by my word.
The mistake I made was to assume that it was one wallet, while it really was another.
What I did was restore an old version of the wallet, which had a known password, and just as you said it had the 100 addresses buffered.
I tested to sign a message, and it works smoothly. I also sent a transaction for testing, and it works as well.