SUMMARY If default kwallet name is changed through kwalletmanager, kwallet-pam fails to unlock a wallet on login. STEPS TO REPRODUCE 1. install kwallet-pam and kwalletmanager 2. change default wallet using kwalletmanager from "kdewallet" to any other wallet, for example, "mywallet". Ensure that this new wallet "mywallet" has password same as "kdewallet". 3. log out and log in again. OBSERVED RESULT New default wallet "mywallet" is locked. Password is being asked to get it unlocked. "kdewallet" is also locked. EXPECTED RESULT New default wallet "mywallet" is unlocked via kwallet-pam. SOFTWARE/OS VERSIONS Linux/KDE Plasma: X11 KDE Plasma Version: 6.4.5 KDE Frameworks Version: 6.18.0 Qt Version: 6.9.3 ADDITIONAL INFORMATION Right on this line: https://invent.kde.org/plasma/kwallet-pam/-/blob/c8a072e4a9af54589f4b0676fac43d8b4b735105/pam_kwallet.c#L785 "kdewallet" wallet name is hardcoded. If kdewallet.salt is different from mywallet.salt, which it likely is, then login password is hashed with incorrect salt, incorrect result is received for default wallet (which is not "kdewallet" but "mywallet"), and "mywallet" is not unlocked. To work correctly, kwallet-pam should find and parse user's kwalletrc for "[Wallet]/Default Wallet" value and if it's present use it instead of hardcoded default "kdewallet".
This is a known and documented limitation. See e.g. https://wiki.archlinux.org/title/KDE_Wallet#Unlock_KDE_Wallet_automatically_on_login (Not saying it can't be changed, but I suspect there was some good reason for it.)