Hi all, I have a laptop in UEFI mode running CentOS 8.2. All works fine but when I enable Secure Boot, login via gdm is no longer possible. Console login is ok. I found some related discussions over on Ubuntu forums, suggesting that this could be related to 3rd-party kernel modules, such as nvidia. This laptop has only Intel builtin graphics, and every single module installed is part of the CentOS distribution. This is from a file /tmp/xses-.XXXXXX (random 6-char string) xrdb: Can't open display '' xmodmap: unable to open display '' Failed to import environment: Process org.freedesktop.systemd1 exited with status 1 /usr/bin/xmbind: Can't open display Unable to init server: Could not connect: Connection refused Something is different in the way Xorg is started. In this situation, the first part of the Xorg log file (under ~/.local) is a dump of X command line options. use: X [:<display>] [options] -a # ... -ac ... ...