SDDM fails to start after boot

Had to pre-format all the text below in order to post it. The forum kept telling me that I was posting links. There are no links below

Booting Manjaro KDE edition from an external USB drive. Intel N100 processor. HMDI cable to an Assus monitor

Boot lands me in a terminal. **systemctl status sddm** yields this:

● sddm.service - Simple Desktop Display Manager
     Loaded: loaded (/usr/lib/systemd/system/sddm.service; enabled; preset: disabled)
     Active: active (running) since Mon 2024-05-06 15:50:12 BST; 1min 1s ago
       Docs: man:sddm(1)
             man:sddm.conf(5)
   Main PID: 772 (sddm)
      Tasks: 2 (limit: 9322)
     Memory: 73.8M (peak: 93.5M)
        CPU: 459ms
     CGroup: /system.slice/sddm.service
             └─772 /usr/bin/sddm

May 06 15:50:27 WD500-azed sddm[772]: Failed to read display number from pipe
May 06 15:50:27 WD500-azed sddm[772]: Display server stopping...
May 06 15:50:27 WD500-azed sddm[772]: Attempt 2 starting the Display server on vt 2 failed
May 06 15:50:29 WD500-azed sddm[772]: Display server starting...
May 06 15:50:29 WD500-azed sddm[772]: Writing cookie to "/run/sddm/xauth_DtdkIb"
May 06 15:50:29 WD500-azed sddm[772]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt2 -auth /run/sddm/xauth_DtdkIb -noreset -displayfd 16
May 06 15:50:31 WD500-azed sddm[772]: Failed to read display number from pipe
May 06 15:50:31 WD500-azed sddm[772]: Display server stopping...
May 06 15:50:31 WD500-azed sddm[772]: Attempt 3 starting the Display server on vt 2 failed
May 06 15:50:31 WD500-azed sddm[772]: Could not start Display server on vt 2

When I try **systemctl restart sddm**, the system seems to make 3 attempts to activate **sddm** (on each occasion the terminal screen disappears in favour of a cursor which blinks twice before I am returned to the terminal)

**Anyone seen this before**?

**Solution ideas**?

**Any help offered, very gratefully received**

**Additional info**:

**uname -r**
6.6.26-1-MANJARO

**lspci**
00:00.0 Host bridge: Intel Corporation Device 461b
00:02.0 VGA compatible controller: Intel Corporation Alder Lake-N [UHD Graphics]
00:08.0 System peripheral: Intel Corporation Device 467e
00:0a.0 Signal processing controller: Intel Corporation Platform Monitoring Technology (rev 01)
00:0d.0 USB controller: Intel Corporation Device 464e
00:14.0 USB controller: Intel Corporation Alder Lake-N PCH USB 3.2 xHCI Host Controller
00:14.2 RAM memory: Intel Corporation Alder Lake-N PCH Shared SRAM
00:14.3 Network controller: Intel Corporation CNVi: Wi-Fi
00:16.0 Communication controller: Intel Corporation Alder Lake-N PCH HECI Controller
00:17.0 SATA controller: Intel Corporation Device 54d3
00:1d.0 PCI bridge: Intel Corporation Device 54b0
00:1d.1 PCI bridge: Intel Corporation Device 54b1
00:1d.3 PCI bridge: Intel Corporation Device 54b3
00:1e.0 Communication controller: Intel Corporation Device 54a8
00:1f.0 ISA bridge: Intel Corporation Alder Lake-N PCH eSPI Controller
00:1f.3 Audio device: Intel Corporation Alder Lake-N PCH High Definition Audio Controller
00:1f.4 SMBus: Intel Corporation Device 54a3
00:1f.5 Serial bus controller: Intel Corporation Device 54a4
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet Controller (rev 15)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller (rev 05)
03:00.0 Non-Volatile memory controller: Phison Electronics Corporation E18 PCIe4 NVMe Controller (rev 01)

**inxi -G**
Graphics:
  Device-1: Intel Alder Lake-N [UHD Graphics] driver: i915 v: kernel
  Display: server: X.org v: 1.21.1.12 driver: X: loaded: intel gpu: i915 tty: 240x67
    resolution: 1920x1080
  API: EGL v: 1.5 drivers: iris,swrast platforms: surfaceless,device
  API: OpenGL v: 4.6 compat-v: 4.5 vendor: mesa v: 24.0.2-manjaro1.1 note: console (EGL sourced)
    renderer: Mesa Intel Graphics (ADL-N), llvmpipe (LLVM 16.0.6 256 bits)
  API: Vulkan v: 1.3.279 drivers: intel surfaces: N/A

**mhwd --list**
e[1me[31m> e[m0000:01:00.0 (0200:10ec:8168) Network controller Realtek Semiconductor Co., Ltd.:
--------------------------------------------------------------------------------
                  NAME               VERSION          FREEDRIVER           TYPE
--------------------------------------------------------------------------------
         network-r8168            2023.09.12                true            PCI


e[1me[31m> e[m0000:00:02.0 (0300:8086:46d0) Display controller Intel Corporation:
--------------------------------------------------------------------------------
                  NAME               VERSION          FREEDRIVER           TYPE
--------------------------------------------------------------------------------
           video-linux            2018.05.04                true            PCI
     video-modesetting            2020.01.13                true            PCI
            video-vesa            2017.03.12                true            PCI

A full boot-log can also be provided

**Note**:

I get the same behaviour with kernel 6.8

Ubuntu 22.04 with kernel 6.5 on the machine's native drive boots without a problem

Continued to investigate. Examination of Xorg.0.log turned up only one error - involving a system (whatever) nmed “uxa”
Reference to “uxa” rang a bell: took a peak into /etc/X11/xorg.conf.d and discovered the culprit: an old configuration file that I’d written back in 2021, /etc/X11/xorg.conf.d/20-intel.conf

Text:
Section “Device”
Identifier “Intel Graphics”
Driver “intel”
Option “AccelMethod” “uxa”
EndSection
#File created by self 15/03/2021 to combat flickering in SSR recordings. See here:
#Troubleshooting - SimpleScreenRecorder - Maarten Baert's website
#Intel graphics - ArchWiki
#https://www.youtube.com/watch?v=v7OJWts_e-4
#The last source also suggests this line: ‘Option “tearfree” “true”’ before AccelMethod
#all changes require reboot to take effect

I commented-out everything in this file out, then did
systemctl restart sddm
and sddm sprang to life

sddm consistently opening on boot

Problem solved

Sorry it wasn’t something less idiosyncratic

Moral: log-files are your friend

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