Just happened today. When the system idled for a while, as usual, screen turned black (due to screensaver setting), then I moved the mouse, and the as usual, the login screen appeared. I typed in the password and hit Return, there’s no response. The login screen appears working with the mouse still responsive. I had to reboot.
I use KDE, never seen this before.
Could caps-lock be on?
Same if you click the button using the mouse? … One thing to try would be to switch to a different TTY and back again. It’s a shot in the dark on my part but I’ve seen this gets around some (maybe similar) issues with SDDM with others on here.
I’d suggest posting some system info as this may help:
inxi -zv8
Note re. Privacy: Potentially sensitive information is filtered out with the z option in that command.
Note that I have renamed your thread — I’ve also moved it to the KDE Plasma category —because what you are talking about is not the login screen (sddm) but the screen locker (kscreenlocker), and while they may look similar, they are two very different software components.
I thought they are the same. They look the same to me.
It didn’t complain about a wrong password. Simply nothing happens. I actually tried typing in the password again.
Well, they’re not. 
Getting back to the topic, do you happen have an Nividia GPU, by any chance?
I don’t think so. It’s a older MacBook Pro.
Can you post the output of… 
inxi -Fxza
… please? You can even do this from the live USB, by the way.
~ inxi -Fxza
System:
Kernel: 6.6.85-2-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 14.2.1
clocksource: tsc avail: acpi_pm
parameters: BOOT_IMAGE=/boot/vmlinuz-6.6-x86_64
root=UUID=06f2f8c6-47ea-444a-97a1-44629f02874f rw quiet splash
resume=UUID=0fc478b2-1d95-466e-bafd-6de6515a989b udev.log_priority=3
Desktop: KDE Plasma v: 6.3.4 tk: Qt v: N/A info: frameworks v: 6.12.0
wm: kwin_wayland vt: 1 dm: SDDM Distro: Manjaro base: Arch Linux
Machine:
Type: Laptop System: Apple product: MacBookPro12,1 v: 1.0
serial: <superuser required> Chassis: type: 9 v: Mac-E43C1C25D4880AD6
serial: <superuser required>
Mobo: Apple model: Mac-E43C1C25D4880AD6 v: MacBookPro12,1
serial: <superuser required> uuid: <superuser required> UEFI: Apple
v: 430.140.3.0.0 date: 04/18/2022
Battery:
ID-1: BAT0 charge: 30.1 Wh (97.7%) condition: 30.8/72.3 Wh (42.6%)
volts: 12.2 min: 11.3 model: SMP bq20z451 type: Li-ion serial: N/A
status: full cycles: 21
CPU:
Info: model: Intel Core i5-5257U bits: 64 type: MT MCP arch: Broadwell
gen: core 5 level: v3 note: check built: 2015-18 process: Intel 14nm
family: 6 model-id: 0x3D (61) stepping: 4 microcode: 0x2F
Topology: cpus: 1x dies: 1 clusters: 2 cores: 2 threads: 4 tpc: 2
smt: enabled cache: L1: 128 KiB desc: d-2x32 KiB; i-2x32 KiB L2: 512 KiB
desc: 2x256 KiB L3: 3 MiB desc: 1x3 MiB
Speed (MHz): avg: 2702 min/max: 500/3100 scaling: driver: intel_cpufreq
governor: schedutil cores: 1: 2702 2: 2702 3: 2702 4: 2702 bogomips: 21606
Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Vulnerabilities:
Type: gather_data_sampling status: Not affected
Type: itlb_multihit status: KVM: VMX disabled
Type: l1tf mitigation: PTE Inversion; VMX: conditional cache flushes, SMT
vulnerable
Type: mds mitigation: Clear CPU buffers; SMT vulnerable
Type: meltdown mitigation: PTI
Type: mmio_stale_data status: Unknown: No mitigations
Type: reg_file_data_sampling status: Not affected
Type: retbleed status: Not affected
Type: spec_rstack_overflow status: Not affected
Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via
prctl
Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer
sanitization
Type: spectre_v2 mitigation: Retpolines; IBPB: conditional; IBRS_FW;
STIBP: conditional; RSB filling; PBRSB-eIBRS: Not affected; BHI: Not
affected
Type: srbds mitigation: Microcode
Type: tsx_async_abort status: Not affected
Graphics:
Device-1: Intel Iris Graphics 6100 vendor: Apple driver: i915 v: kernel
arch: Gen-8 process: Intel 14nm built: 2014-15 ports: active: eDP-1
empty: DP-1, DP-2, HDMI-A-1, HDMI-A-2 bus-ID: 00:02.0 chip-ID: 8086:162b
class-ID: 0300
Display: wayland server: X.org v: 1.21.1.16 with: Xwayland v: 24.1.6
compositor: kwin_wayland driver: X: loaded: modesetting
alternate: fbdev,vesa dri: iris gpu: i915 display-ID: 0
Monitor-1: eDP-1 model: Apple Color LCD built: 2013 res: mode: 2560x1600
hz: 60 scale: 100% (1) dpi: 227 gamma: 1.2 size: 286x179mm (11.26x7.05")
diag: 337mm (13.3") ratio: 16:10 modes: 2560x1600
API: EGL v: 1.5 hw: drv: intel iris platforms: device: 0 drv: iris
device: 1 drv: swrast gbm: drv: iris surfaceless: drv: iris wayland:
drv: iris x11: drv: iris
API: OpenGL v: 4.6 compat-v: 4.5 vendor: intel mesa v: 25.0.3-arch1.1
glx-v: 1.4 direct-render: yes renderer: Mesa Intel Iris Graphics 6100 (BDW
GT3) device-ID: 8086:162b memory: 3.74 GiB unified: yes display-ID: :1.0
API: Vulkan v: 1.4.309 layers: N/A device: 0 type: integrated-gpu
name: Intel Iris Graphics 6100 (BDW GT3) driver: mesa intel
v: 25.0.3-arch1.1 device-ID: 8086:162b surfaces: xcb,xlib,wayland
Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo
de: kscreen-console,kscreen-doctor gpu: gputop, intel_gpu_top, lsgpu
wl: wayland-info x11: xdpyinfo, xprop, xrandr
Audio:
Device-1: Intel Broadwell-U Audio vendor: Apple driver: snd_hda_intel
v: kernel bus-ID: 00:03.0 chip-ID: 8086:160c class-ID: 0403
Device-2: Intel Wildcat Point-LP High Definition Audio
driver: snd_hda_intel v: kernel bus-ID: 00:1b.0 chip-ID: 8086:9ca0
class-ID: 0403
Device-3: Broadcom 720p FaceTime HD Camera driver: N/A pcie: gen: 2
speed: 5 GT/s lanes: 1 bus-ID: 02:00.0 chip-ID: 14e4:1570 class-ID: 0480
API: ALSA v: k6.6.85-2-MANJARO status: kernel-api with: aoss
type: oss-emulator tools: alsactl,alsamixer,amixer
Server-1: JACK v: 1.9.22 status: off tools: N/A
Server-2: PipeWire v: 1.4.1 status: off with: wireplumber status: active
tools: pw-cli,wpctl
Server-3: PulseAudio v: 17.0-43-g3e2bb status: active
with: pulseaudio-alsa type: plugin tools: pacat,pactl
Network:
Device-1: Broadcom BCM43602 802.11ac Wireless LAN SoC vendor: Apple
driver: brcmfmac v: kernel pcie: gen: 1 speed: 2.5 GT/s lanes: 1
bus-ID: 03:00.0 chip-ID: 14e4:43ba class-ID: 0280
IF: wlp3s0 state: up mac: <filter>
Info: services: NetworkManager, systemd-timesyncd, wpa_supplicant
Bluetooth:
Device-1: Apple Bluetooth Host Controller driver: btusb,hid-generic,usbhid
type: USB rev: 2.0 speed: 12 Mb/s lanes: 1 mode: 1.1 bus-ID: 1-3:2
chip-ID: 05ac:8290 class-ID: fe01
Report: rfkill ID: hci0 rfk-id: 1 state: down bt-service: enabled,running
rfk-block: hardware: no software: yes address: see --recommends
Drives:
Local Storage: total: 233.76 GiB used: 141.39 GiB (60.5%)
SMART Message: Unable to run smartctl. Root privileges required.
ID-1: /dev/sda maj-min: 8:0 vendor: Apple model: SSD SM0256G
size: 233.76 GiB block-size: physical: 4096 B logical: 512 B speed: 6.0 Gb/s
tech: SSD serial: <filter> fw-rev: PA0Q scheme: GPT
Partition:
ID-1: / raw-size: 48.83 GiB size: 47.76 GiB (97.81%) used: 34.6 GiB (72.4%)
fs: ext4 dev: /dev/sda3 maj-min: 8:3
ID-2: /boot/efi raw-size: 1001 MiB size: 999 MiB (99.80%)
used: 300 KiB (0.0%) fs: vfat dev: /dev/sda1 maj-min: 8:1
ID-3: /home raw-size: 174.19 GiB size: 170.4 GiB (97.82%)
used: 100.05 GiB (58.7%) fs: ext4 dev: /dev/sda4 maj-min: 8:4
Swap:
Kernel: swappiness: 60 (default) cache-pressure: 100 (default) zswap: yes
compressor: zstd max-pool: 20%
ID-1: swap-1 type: partition size: 9.77 GiB used: 6.63 GiB (67.9%)
priority: -2 dev: /dev/sda2 maj-min: 8:2
Sensors:
System Temperatures: cpu: 79.0 C pch: 69.5 C mobo: N/A
Fan Speeds (rpm): N/A
Info:
Memory: total: 8 GiB available: 7.66 GiB used: 6.93 GiB (90.4%)
Processes: 217 Power: uptime: 10h 29m states: freeze,mem,disk
suspend: deep avail: s2idle wakeups: 1 hibernate: platform avail: shutdown,
reboot, suspend, test_resume image: 3.05 GiB
services: org_kde_powerdevil,upowerd Init: systemd v: 257
default: graphical tool: systemctl
Packages: 1741 pm: pacman pkgs: 1735 libs: 461 tools: octopi,pamac,yay
pm: flatpak pkgs: 6 Compilers: clang: 19.1.7 gcc: 14.2.1 Shell: Zsh v: 5.9
running-in: konsole inxi: 3.3.38
➜ ~
Well, I see nothing out of the ordinary in your hardware — everything should be well supported. 
You have also not told us whether the phenomenon has occurred again, or whether this was just a one-time event. If the latter, then it could have been due to atmospheric conditions or even cosmic radiation, and then I wouldn’t worry too much about it.
If the former, then I would first and foremost advise you to run memtest86+ on the device and let it run for at least 24 hours, because then there is a chance that you’ve got a faulty memory module.
Also, if you are using any of the non-default themes, then if the theme is too old, it may cause compatibility issues. But I guess then you would have had problems sooner already, so I think we can exclude that possibility.
haven’t seen it a second time yet. Will keep you posted or run memtest86.
Speaking of memory, I wonder some memory heavy processes I run (as I often do) can cause some system processes be swapped out or killed thus resulting this issue?
In theory, the system can kill processes if there’s not enough available memory anymore — it is known as the oomkiller (“out-of-memory killer”) — but considering that you’ve got 8 GiB of RAM and a swap partition of roughly the same size, I doubt whether that would be the case here.
I suspect that it was probably just a glitch due to atmospheric influences or cosmic radiation. Consumer-grade hardware does not have error correction built in, and therefore it is quite possible for some bits in RAM to get flipped due to cosmic radiation, or due to a buildup of static electricity in the air — usually as the result of weather changes and/or fierce winds.
Still, it’s never a bad idea — especially on an old machine like that — to check the RAM for errors, though.
I have currently the same issue since 2 or 3 updates, sometimes (not always) when the screen is locked, i move the mouse, the login screen appears, type in my password, hit return and nothing happen, no response.
Then, if i hit Esc, then move the mouse again, type in my password and it works. I do not have to restart my system.
The error related i see in my logs are the following :
kscreenlocker_greet[87921]: Failed to write to the pipe: Bad file descriptor.
kscreenlocker_greet[87921]: qt.qpa.wayland: Could not create EGL surface (EGL error 0x3003)
I changed my sddm theme without any effect.
This is not related with heavy process or lack of RAM, i have a quite recent Nvidia card, core i5 12th gen.
inxi -Fxza
System:
Kernel: 6.14.6-1-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 15.1.1
clocksource: tsc avail: acpi_pm
parameters: BOOT_IMAGE=/@/boot/vmlinuz-6.14-x86_64
root=UUID=0701ca92-2b7e-41c0-b4dd-d91194313cdf rw rootflags=subvol=@
cryptdevice=UUID=d916a464-4abf-46bd-b36a-e81a6381e0fc:luks-d916a464-4abf-46bd-b36a-e81a6381e0fc
root=/dev/mapper/luks-d916a464-4abf-46bd-b36a-e81a6381e0fc
udev.log_priority=3 nvidia-drm.modeset=1 nvidia_drm.fbdev=1
NVreg_PreserveVideoMemoryAllocations=1 ipv6.disable=1
Desktop: KDE Plasma v: 6.3.5 tk: Qt v: N/A info: frameworks v: 6.13.0
wm: kwin_x11 vt: 2 dm: SDDM Distro: Manjaro base: Arch Linux
Machine:
Type: Desktop Mobo: BIOSTAR model: B660T-SILVER serial: <superuser required>
uuid: <superuser required> UEFI: American Megatrends LLC. v: 5.27
date: 09/12/2023
CPU:
Info: model: 12th Gen Intel Core i5-12400F bits: 64 type: MT MCP
arch: Alder Lake gen: core 12 level: v3 note: check built: 2021+
process: Intel 7 (10nm ESF) family: 6 model-id: 0x97 (151) stepping: 2
microcode: 0x38
Topology: cpus: 1x dies: 1 clusters: 6 cores: 6 threads: 12 tpc: 2
smt: enabled cache: L1: 480 KiB desc: d-6x48 KiB; i-6x32 KiB L2: 7.5 MiB
desc: 6x1.2 MiB L3: 18 MiB desc: 1x18 MiB
Speed (MHz): avg: 780 min/max: 800/5600 scaling: driver: intel_pstate
governor: powersave cores: 1: 780 2: 780 3: 780 4: 780 5: 780 6: 780 7: 780
8: 780 9: 780 10: 780 11: 780 12: 780 bogomips: 59904
Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Vulnerabilities:
Type: gather_data_sampling status: Not affected
Type: ghostwrite status: Not affected
Type: itlb_multihit status: Not affected
Type: l1tf status: Not affected
Type: mds status: Not affected
Type: meltdown status: Not affected
Type: mmio_stale_data status: Not affected
Type: reg_file_data_sampling status: Not affected
Type: retbleed status: Not affected
Type: spec_rstack_overflow status: Not affected
Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via
prctl
Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer
sanitization
Type: spectre_v2 mitigation: Enhanced / Automatic IBRS; IBPB:
conditional; PBRSB-eIBRS: SW sequence; BHI: BHI_DIS_S
Type: srbds status: Not affected
Type: tsx_async_abort status: Not affected
Graphics:
Device-1: NVIDIA GA107 [GeForce RTX 3050 6GB] driver: nvidia v: 570.144
alternate: nouveau,nvidia_drm non-free: 550-570.xx+ status: current (as of
2025-04; EOL~2026-12-xx) arch: Ampere code: GAxxx process: TSMC n7 (7nm)
built: 2020-2023 pcie: gen: 4 speed: 16 GT/s lanes: 8 link-max: lanes: 16
ports: active: none off: DP-1 empty: DVI-D-1,HDMI-A-1 bus-ID: 01:00.0
chip-ID: 10de:2584 class-ID: 0300
Device-2: Sunplus Innovation Angetube Live Camera
driver: snd-usb-audio,uvcvideo type: USB rev: 2.0 speed: 480 Mb/s lanes: 1
mode: 2.0 bus-ID: 1-4:3 chip-ID: 1bcf:7550 class-ID: 0102 serial: <filter>
Display: x11 server: X.Org v: 21.1.16 with: Xwayland v: 24.1.6
compositor: kwin_x11 driver: X: loaded: nvidia gpu: nvidia,nvidia-nvswitch
display-ID: :0 screens: 1
Screen-1: 0 s-res: 2560x1440 s-dpi: 108 s-size: 602x342mm (23.70x13.46")
s-diag: 692mm (27.26")
Monitor-1: DP-1 mapped: DP-0 note: disabled model: Idek Iiyama PL2760Q
serial: <filter> built: 2021 res: N/A dpi: 109 gamma: 1.2
size: 527x296mm (20.75x11.65") diag: 685mm (27") ratio: 16:9 modes:
max: 2560x1440 min: 640x480
API: EGL v: 1.5 hw: drv: nvidia nouveau drv: nvidia platforms: device: 0
drv: nvidia device: 1 drv: nouveau device: 2 drv: swrast gbm: drv: nvidia
surfaceless: drv: nvidia x11: drv: nvidia inactive: wayland
API: OpenGL v: 4.6.0 compat-v: 4.5 vendor: nvidia mesa v: 570.144
glx-v: 1.4 direct-render: yes renderer: NVIDIA GeForce RTX 3050/PCIe/SSE2
memory: 5.86 GiB
API: Vulkan v: 1.4.309 layers: 5 device: 0 type: discrete-gpu
name: NVIDIA GeForce RTX 3050 driver: nvidia v: 570.144 device-ID: 10de:2584
surfaces: xcb,xlib
Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo
de: kscreen-console,kscreen-doctor gpu: nvidia-settings,nvidia-smi
wl: wayland-info x11: xdpyinfo, xprop, xrandr
Audio:
Device-1: Intel Alder Lake-S HD Audio vendor: Biostar Microtech Intl Corp
driver: snd_hda_intel v: kernel alternate: snd_soc_avs,snd_sof_pci_intel_tgl
bus-ID: 00:1f.3 chip-ID: 8086:7ad0 class-ID: 0403
Device-2: NVIDIA GA107 High Definition Audio driver: snd_hda_intel
v: kernel pcie: gen: 4 speed: 16 GT/s lanes: 8 link-max: lanes: 16
bus-ID: 01:00.1 chip-ID: 10de:2291 class-ID: 0403
Device-3: Sunplus Innovation Angetube Live Camera
driver: snd-usb-audio,uvcvideo type: USB rev: 2.0 speed: 480 Mb/s lanes: 1
mode: 2.0 bus-ID: 1-4:3 chip-ID: 1bcf:7550 class-ID: 0102 serial: <filter>
Device-4: Texas Instruments PCM2704 16-bit stereo audio DAC
driver: hid-generic,snd-usb-audio,usbhid type: USB rev: 1.1 speed: 12 Mb/s
lanes: 1 mode: 1.1 bus-ID: 1-5:4 chip-ID: 08bb:2704 class-ID: 0300
API: ALSA v: k6.14.6-1-MANJARO status: kernel-api with: aoss
type: oss-emulator tools: alsactl,alsamixer,amixer
Server-1: JACK v: 1.9.22 status: off tools: N/A
Server-2: PipeWire v: 1.4.2 status: active with: 1: pipewire-pulse
status: active 2: wireplumber status: active 3: pipewire-alsa type: plugin
tools: pactl,pw-cat,pw-cli,wpctl
Network:
Device-1: Realtek RTL8125 2.5GbE vendor: Biostar Microtech Intl Corp
driver: r8169 v: kernel pcie: gen: 2 speed: 5 GT/s lanes: 1 port: 3000
bus-ID: 04:00.0 chip-ID: 10ec:8125 class-ID: 0200
IF: enp4s0 state: up speed: 2500 Mbps duplex: full mac: <filter>
IF-ID-1: virbr0 state: down mac: <filter>
IF-ID-2: wg0-mullvad state: unknown speed: N/A duplex: N/A mac: N/A
Info: services: NetworkManager, ntpd, wpa_supplicant
RAID:
Hardware-1: Intel Volume Management Device NVMe RAID Controller driver: vmd
v: 0.6 port: N/A bus-ID: 00:0e.0 chip-ID: 8086:467f rev: class-ID: 0104
Drives:
Local Storage: total: 5.01 TiB used: 2.27 TiB (45.3%)
SMART Message: Unable to run smartctl. Root privileges required.
ID-1: /dev/nvme0n1 maj-min: 259:0 vendor: Samsung model: SSD 990 PRO 2TB
size: 1.82 TiB block-size: physical: 512 B logical: 512 B speed: 63.2 Gb/s
lanes: 4 tech: SSD serial: <filter> fw-rev: 4B2QJXD7 temp: 57.9 C
scheme: GPT
ID-2: /dev/nvme1n1 maj-min: 259:5 vendor: Mushkin model: MKNSSDVT2TB-D8
size: 1.82 TiB block-size: physical: 512 B logical: 512 B speed: 63.2 Gb/s
lanes: 4 tech: SSD serial: <filter> fw-rev: 3.H.J.22 temp: 65.8 C
scheme: GPT
ID-3: /dev/sda maj-min: 8:0 vendor: Crucial model: CT512MX100SSD1
size: 476.94 GiB block-size: physical: 4096 B logical: 512 B speed: 6.0 Gb/s
tech: SSD serial: <filter> fw-rev: MU03 scheme: GPT
ID-4: /dev/sdb maj-min: 8:16 vendor: Western Digital
model: WD10TPVT-00U4RT1 size: 931.51 GiB block-size: physical: 512 B
logical: 512 B type: USB rev: 3.0 spd: 5 Gb/s lanes: 1 mode: 3.2 gen-1x1
tech: HDD rpm: 5200 serial: <filter> fw-rev: 01.0 scheme: MBR
Partition:
ID-1: / raw-size: 312.5 GiB size: 312.5 GiB (100.00%)
used: 143.59 GiB (45.9%) fs: btrfs dev: /dev/dm-0 maj-min: 253:0
mapped: luks-d916a464-4abf-46bd-b36a-e81a6381e0fc
ID-2: /boot/efi raw-size: 400 MiB size: 399.2 MiB (99.80%)
used: 728 KiB (0.2%) fs: vfat dev: /dev/nvme0n1p1 maj-min: 259:1
ID-3: /home raw-size: 195.31 GiB size: 191.19 GiB (97.89%)
used: 138.92 GiB (72.7%) fs: ext4 dev: /dev/dm-1 maj-min: 253:1
mapped: luks-c3e0e757-8f71-4642-bce0-fa52246af02a
ID-4: /var/log raw-size: 312.5 GiB size: 312.5 GiB (100.00%)
used: 143.59 GiB (45.9%) fs: btrfs dev: /dev/dm-0 maj-min: 253:0
mapped: luks-d916a464-4abf-46bd-b36a-e81a6381e0fc
Swap:
Alert: No swap data was found.
Sensors:
System Temperatures: cpu: 37.0 C mobo: N/A gpu: nvidia temp: 54 C
Fan Speeds (rpm): N/A gpu: nvidia fan: 0%
Info:
Memory: total: 16 GiB available: 15.45 GiB used: 5.43 GiB (35.2%)
Processes: 476 Power: uptime: 21h 5m states: freeze,mem,disk suspend: deep
avail: s2idle wakeups: 0 hibernate: platform avail: shutdown, reboot,
suspend, test_resume image: 6.1 GiB services: org_kde_powerdevil,
power-profiles-daemon, upowerd Init: systemd v: 257 default: graphical
tool: systemctl
Packages: 1842 pm: dpkg pkgs: 0 pm: pacman pkgs: 1823 libs: 445
tools: pamac,yay pm: flatpak pkgs: 19 Compilers: clang: 19.1.7 gcc: 15.1.1
Shell: Zsh v: 5.9 running-in: konsole inxi: 3.3.38