Ubuntu 18.04 cannot boot

Question

I installed Ubuntu 18.04. At first, it used to automatically reboot from time to time. Now, I cannot boot it. The system shows this message and reboot again and then shows the same message over and over again. What should I do? Is it a hardware problem?

The messages are:

[  0.049316] ACPI Error:[_SB_.PCI0.RP05.PXSX] Namespace lookup failure, AE_NOT_FOUND(20170831/dswload2-191)
[  0.049324] ACPI Exception:AE_NOT_FOUND,During name lookup/catalog(20170831/psobject-252)
[ 0.049328] ACPI Error: Method parse/execution failed \_SB.PCI0.RP04.PXSX, AE_NOT_FOUND (20170831/psparse-550)
[  0.049682] ACPI Error:[_SB_.PCI0.RP09.PXSX] Namespace lookup failure, AE_NOT_FOUND(20170831/dswload2-191)
[  0.049687] ACPI Exception:AE_NOT_FOUND,During name lookup/catalog(20170831/psobject-252)
[ 0.049689] ACPI Error: Method parse/execution failed \_SB.PCI0.RP08.PXSX, AE_NOT_FOUND (20170831/psparse-550)
[  0.849684] pcieport 0000:00:ac.4: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=00e4(Receiver ID)
[  0.849707] pcieport 0000:00:ac.4: device [8086:a294]error status/mask-=00000001/00002000
[  0.849725] pcieport 0000:00:ac.4: [ 0] Receiver Error   (First)

Answer 1

If you can access the file system of your machine somehow (e.g. by using windows if you have a dual boot), try to modify the configuration file: /etc/rc.local

Write & save the following line:

echo "disable" > /sys/firmware/acpi/interrupts/gpe6F

I found it on bugzilla where somebody got a very similar error on startup. Perhaps you can find more in the thread.