подпись не подписана доверенным ключом

Мой X11 Desktop в эти дни ломался по той же причине

/var/log/kern.log:Oct  9 14:55:29 alpha kernel: [   51.560789] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 10 20:53:30 alpha kernel: [    1.316375] Initialise system trusted keyrings
/var/log/kern.log:Oct 10 20:53:30 alpha kernel: [    1.566875] Key type trusted registered
/var/log/kern.log:Oct 10 20:53:30 alpha kernel: [   49.866048] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 10 20:53:31 alpha kernel: [   52.359018] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 10 20:53:31 alpha kernel: [   52.607128] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 10 20:53:31 alpha kernel: [   52.609413] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 10 20:53:31 alpha kernel: [   52.611961] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 05:21:14 alpha kernel: [    1.332628] Initialise system trusted keyrings
/var/log/kern.log:Oct 11 05:21:14 alpha kernel: [    1.586145] Key type trusted registered
/var/log/kern.log:Oct 11 05:21:14 alpha kernel: [   48.973431] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 05:21:15 alpha kernel: [   51.242295] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 05:21:15 alpha kernel: [   51.496355] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 05:21:15 alpha kernel: [   51.499499] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 05:21:15 alpha kernel: [   51.504483] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 14:42:55 alpha kernel: [    1.332616] Initialise system trusted keyrings
/var/log/kern.log:Oct 11 14:42:55 alpha kernel: [    1.590843] Key type trusted registered
/var/log/kern.log:Oct 11 14:42:55 alpha kernel: [   48.803714] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 14:42:56 alpha kernel: [   51.291135] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 14:42:56 alpha kernel: [   51.536567] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 14:42:56 alpha kernel: [   51.540598] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 14:42:56 alpha kernel: [   51.543458] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 19:55:41 alpha kernel: [    1.332554] Initialise system trusted keyrings
/var/log/kern.log:Oct 11 19:55:41 alpha kernel: [    1.592800] Key type trusted registered
/var/log/kern.log:Oct 11 19:55:41 alpha kernel: [   48.956084] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 19:55:42 alpha kernel: [   51.173503] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 19:55:42 alpha kernel: [   51.414123] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 19:55:42 alpha kernel: [   51.416660] PKCS#7 signature not signed with a trusted key
/var/log/kern.log:Oct 11 19:55:42 alpha kernel: [   51.419845] PKCS#7 signature not signed with a trusted key
/var/log/syslog:Oct  9 10:16:58 alpha kernel: [    1.316754] Initialise system trusted keyrings

Моя машина:

$ neofetch
            .-/+oossssoo+/-.               gaowei@alpha
        `:+ssssssssssssssssss+:`           ------------
      -+ssssssssssssssssssyyssss+-         OS: Ubuntu 19.04 x86_64
    .ossssssssssssssssssdMMMNysssso.       Host: MacBookPro11,1 1.0
   /ssssssssssshdmmNNmmyNMMMMhssssss/      Kernel: 5.0.0-29-generic
  +ssssssssshmydMMMMMMMNddddyssssssss+     Uptime: 19 hours, 52 mins
 /sssssssshNMMMyhhyyyyhmNMMMNhssssssss/    Packages: 2367 (dpkg), 4 (snap)
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Shell: bash 5.0.3
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   Resolution: 2560x1600
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   DE: KDE
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   WM: KWin
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   Theme: Breeze [KDE], Breeze [GTK3]
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Icons: breeze [KDE], breeze [GTK3]
 /sssssssshNMMMyhhyyyyhdNMMMNhssssssss/    Terminal: alacritty
  +sssssssssdmydMMMMMMMMddddyssssssss+     CPU: Intel i5-4258U (4) @ 2.900GHz
   /ssssssssssshdmNNNNmyNMMMMhssssss/      GPU: Intel Haswell-ULT
    .ossssssssssssssssssdMMMNysssso.       Memory: 2457MiB / 3850MiB
      -+sssssssssssssssssyyyssss+-
        `:+ssssssssssssssssss+:`