diff --git a/admin-guide/troubleshooting/login.md b/admin-guide/troubleshooting/login.md
index 29200752..6c16cbfb 100644
--- a/admin-guide/troubleshooting/login.md
+++ b/admin-guide/troubleshooting/login.md
@@ -28,6 +28,12 @@ pam_sss(sshd:account): Access denied for user xxxxxx_y: 4 (System error)
 ```
 Here the AD join might be broken. The machine can be rejoined by deleting/moving away `/etc/krb5.keytab` and then running Puppet (`puppet agent -t`).
 
+```
+pam_sss(xrdp-sesman:auth): received for user xxxxxx_y: 10 (User not known to the underlying authentication module)
+```
+can be caused by corrupt `sssd` cache files (see [SSD Troubleshooting](sssd#check-log-for-ad-connection))
+
+
 ### KioskWithKeyboard Error
 ```
 gnome-session[31143]: gnome-session-binary[31143]: dconf-WARNING: unable to open named profile (redhatkiosk): using the null configuration.