GDM3 and Lightdm fail at startup

What video chip and drivers are you using?

Hi, sorry, for the late answer.

lspci
00:00.0 Host bridge: Intel Corporation 8th Gen Core Processor Host Bridge/DRAM Registers (rev 0d)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) (rev 0d)
00:01.1 PCI bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x8) (rev 0d)
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile) (rev 02)
00:04.0 Signal processing controller: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 0d)
00:08.0 System peripheral: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model
00:12.0 Signal processing controller: Intel Corporation Cannon Lake PCH Thermal Controller (rev 10)
00:14.0 USB controller: Intel Corporation Cannon Lake PCH USB 3.1 xHCI Host Controller (rev 10)
00:14.2 RAM memory: Intel Corporation Cannon Lake PCH Shared SRAM (rev 10)
00:15.0 Serial bus controller [0c80]: Intel Corporation Cannon Lake PCH Serial IO I2C Controller #0 (rev 10)
00:15.1 Serial bus controller [0c80]: Intel Corporation Cannon Lake PCH Serial IO I2C Controller #1 (rev 10)
00:16.0 Communication controller: Intel Corporation Cannon Lake PCH HECI Controller (rev 10)
00:16.3 Serial controller: Intel Corporation Cannon Lake PCH Active Management Technology - SOL (rev 10)
00:17.0 SATA controller: Intel Corporation Cannon Lake Mobile PCH SATA AHCI Controller (rev 10)
00:1c.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #1 (rev f0)
00:1c.5 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #6 (rev f0)
00:1c.6 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #7 (rev f0)
00:1d.0 PCI bridge: Intel Corporation Cannon Lake PCH PCI Express Root Port #9 (rev f0)
00:1f.0 ISA bridge: Intel Corporation Device a30e (rev 10)
00:1f.3 Audio device: Intel Corporation Cannon Lake PCH cAVS (rev 10)
00:1f.4 SMBus: Intel Corporation Cannon Lake PCH SMBus Controller (rev 10)
00:1f.5 Serial bus controller [0c80]: Intel Corporation Cannon Lake PCH SPI Controller (rev 10)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (7) I219-LM (rev 10)
02:00.0 3D controller: NVIDIA Corporation GP108M [GeForce MX150] (rev a1)
03:00.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02)
04:00.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02)
04:01.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02)
04:02.0 PCI bridge: Intel Corporation JHL6340 Thunderbolt 3 Bridge (C step) [Alpine Ridge 2C 2016] (rev 02)
05:00.0 System peripheral: Intel Corporation JHL6340 Thunderbolt 3 NHI (C step) [Alpine Ridge 2C 2016] (rev 02)
3b:00.0 USB controller: Intel Corporation JHL6340 Thunderbolt 3 USB 3.1 Controller (C step) [Alpine Ridge 2C 2016] (rev 02)
3c:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader (rev 01)
3d:00.0 Network controller: Intel Corporation Wi-Fi 6 AX200 (rev 1a)
3e:00.0 Non-Volatile memory controller: SK hynix Device 1627

Does this help?

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Well, the problem is still there. Anybody with an idea? it seems to be
related to a kernel issue ...

Am 21.05.21 um 11:41 schrieb Launchpad Janitor:
> Your question #696777 on Ubuntu changed:
> https://answers.launchpad.net/ubuntu/+question/696777
>
> Status: Open => Expired
>
> Launchpad Janitor expired the question:
> This question was expired because it remained in the 'Open' state
> without activity for the last 15 days.
>

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Due to this issue, I refrain from restarting the computer a lot. Now, I had to. So I can report: The issue exists in
Linux 5.4.0-74-generic #82-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux

but not in
Linux 5.4.0-73-generic #82-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux

Or in 5.4.0-71-generic ... still no clue of how to avoid this.

This question was expired because it remained in the 'Open' state without activity for the last 15 days.