session lock screen dies when removing external monitor while locked

[jkraemer]

Hyprland version

v0.56.2

Is this a regression?

Don't know

What's the bug?

I usually have an external monitor attached to my notebook and the notebook lcd disabled. when the lock screen (I use DMS/quickshell) is displayed and I disconnect the monitor, I very often get the 'oopsie daisy your lock screen died' error shown on the notebook and the session is stuck until I recover it from a TTY. Hyprland log shows onGetLockSurface: monitor is gone for output resource and quickshell logs wl_display#1: error 0: invalid object N

I've had Claude Code diagnose this, it reproduced the issue and came up with a patch. I'll post it upon request since I honestly don't have the bandwidth to 'fully understand' what's going on there. The gist of it is that onGetLockSurface in src/protocols/SessionLock.cpp returns too early, leading to a missing resource which then leads to failing communication between lock screen and hyprland.

Reproduction steps

1. Have a laptop with an external monitor, and the laptop panel disabled via a monitor rule while the external is connected, it is re-enabled by a config reload on unplug.
2. Lock the session with an ext-session-lock client (I use DMS)
3. Unplug external monitor

Result is the 'your lockscreen died' screen on the Notebook LCD in most cases, but sometimes it works as expected and the lock screen is shown.

Relevant part of my hyprland.lua:

-- External monitor (LG ULTRAFINE) - use description to be port-independent
hl.monitor({ output = "desc:LG Electronics LG ULTRAFINE", mode = "preferred", position = "auto", scale = 1.33333 })

-- Laptop screen (built-in). Switched off whenever an external monitor is
-- present, so the external one is the sole display.
local laptop = { output = "eDP-1", mode = "preferred", position = "auto", scale = 1.33333 }

-- FALLBACK is the headless output Hyprland creates while no real monitor is
-- enabled; it must not keep the laptop screen off.
local function external_monitor_present()
    for _, m in ipairs(hl.get_monitors()) do
        if m.name ~= laptop.output and m.name ~= "FALLBACK" then return true end
    end
    return false
end

-- Monitor rules only take effect when the config is loaded, so the rule is
-- chosen here at load time and monitor hotplug triggers a reload.
if external_monitor_present() then
    hl.monitor({ output = laptop.output, disabled = true })
else
    hl.monitor(laptop)
end

local function reload_monitor_layout()
    hl.exec_cmd("hyprctl reload")
end

hl.on("monitor.added", reload_monitor_layout)
hl.on("monitor.removed", reload_monitor_layout)

-- Fallback for any other monitors
hl.monitor({ output = "", mode = "preferred", position = "auto", scale = "auto" })

Attachments

systeminfo.txt
dms-journal.log
hyprland-excerpt.log

I acknowledge that:

• I have searched all (open and closed) discussions and issues and my problem is not there.

• I have read the Code of Conduct and agree to follow it.

• I wrote this request with my own hands, my own keyboard, and in my own words.

[cjk]

Same here with AMD, but only after upgrading to 0.57

[vaxerski]

#16784