Comment 16 for bug 1504626

This may be related to the KDE wallet migration wizard? From journalctl:

org.kde.kwalletd5[1416]: Setting useNewHash to true
org.kde.kwalletd5[1416]: Wallet new enough, using new hash
org.kde.kwalletd5[1416]: fsize: 2918082162 encrypted.size(): 86560 blksz: 8
org.kde.kwalletd5[1416]: Application ' "KDE Wallet Migration Agent" ' using kwallet without parent window!
org.kde.kwalletd5[1416]: Setting useNewHash to true
org.kde.kwalletd5[1416]: Wallet new enough, using new hash
org.kde.kwalletd5[1416]: Migration failed.
org.kde.kwalletd5[1416]: Migration wizard returned an error or has been canceled. The migration agent will resume upon next daemon start
org.kde.kwalletd5[1416]: Migration agent stop.

sddm[1099]: Checking for pam module
sddm[1099]: Got pam-login
sddm[1099]: kwalletd: Waiting for hash on 17-
sddm[1099]: kwalletd: waitingForEnvironment on: 21
sddm[1099]: kwalletd: Couldn't accept incoming connection
sddm[1099]: Hash or environment not received