Probably doesn't help for recovery, but you can set an empty password and use polkit-based access control for wallets. You just need to check the box that says programs need to ask for access in Settings > KDE Wallet > Access Control Tab (not KWalletManager). Afterwards you will get a popup the first time they do and can then choose to give them permanent access.
KDE
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE’s software runs on GNU/Linux, BSD and other operating systems, including Windows.
Plasma 6 Bugs
If you encounter a bug, proceed to https://bugs.kde.org/, check whether it has been reported.
If it hasn't, report it yourself.
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Developers do not look for reports on social media, so they will not see it and all it does is clutter up the feed.
I have yet to understand why Kwallet does the things it does sometimes. It varies by distro, and sometimes you fix it by putting in your login password, sometimes by putting in no password, sometimes make a new wallet, sometimes wipe the database. It's pretty frustrating.
If you can't change the password on the original keychain, I don't think there's a way to recover anything stored in it.
That is what I feared. I tried both my login password and a blank password, and it refuses to open. I'll wait to see if anyone has previously found a way to magically open it again, but I will probably need to scrap my Signal database and relink my computer without the chat history. It's a bummer, but not a major issue for me.
The password could be the same as your login password?
I would have assumed so, but it is not accepted.
Hmm, the only other thing I can think of is that the wallet somehow got corrupted. Did you do a normal shutdown / restart? Is this after an update?
I did an update over the week end, but I am pretty sure I rebooted between then and startup today. It is a long time since I've had to force shutdown.
Just to be sure, you didn't either change your login password since your last reboot, right?
Nope.
You need kwallet_pam installed and configured right to make auto unlock work using your login password
Auto unlock seems to work completely fine with the new wallet I set up. And it tries to unlock the one I am having issues with (called "Default keyring"), but it seems the password just isn't accepted anymore (whatever it was).
I don't have any process named kwallet_pam running (only kwalletd6), and could not find anything related to kwallet_pam as an executable at least.