How to enable unlisted user login to LIGHTDM

edit /etc/lightdm/lightdm.conf.d/40-enable-guest.conf and add:

[Seat:*]
allow-guest=false

[SeatDefaults]
greeter-show-manual-login=true

[Seat:*]
greeter-show-manual-login=true

BTW:

• You need to be ROOT to accomplish this.
• The name 40-enable-guest can be something else
• Tested on Lubuntu 24.04 and 22.04 January 2026

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