[UNSOLVED] ACPI Error: [CAPB] Namespace lookup failure, AE_ALREADY_EXISTS - what does this error on booting mean & how do I resolve it?

Similar benign error message to all these...


Have a read through for more details.

Thanks sueridgepipe for your reply.
I notice that the other similar posts you indicated had AE_DOESNT_EXIST, whereas it's the opposite in my case - it does exist. What does 'AE' stand for - is it ACPI Error?

I should mention there isn't a problem with the brightness control (Fn keys) - I know ACPI errors can be related to this. I had a look inside the grub file using gksudo mousepad /etc/default/grub
and got the following output. Maybe I need to modify the line
GRUB_CMDLINE_LINUX_DEFAULT="quiet" in some way, i.e. the "splash" bit, but as I say there is no problem with the brightness keys. Here is the output from terminal:


# If you want to enable the save default function, uncomment the following
# line, and set GRUB_DEFAULT to saved.

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable Hidden Menu, and optionally hide the timeout count

# Uncomment to use basic console

# Uncomment to disable graphical terminal

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'

# Uncomment to allow the kernel use the same resolution used by grub

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"

# Uncomment to disable generation of recovery mode menu entries

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.

# Uncomment one of them for the gfx desired, a image background or a gfxtheme

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

I dug a bit deeper on the internet to see if I could find a solution. So far, I didn't find anything useful. I don't know whether this helps, not understanding the significance of everything the terminal is giving me, except that there's obviously an error of some sort:

[mike@NP-N145 ~]$ dmesg | grep -2 Err
[    0.305793] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-3f])
[    0.305810] acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments MSI]
[    0.305958] ACPI Error: [CAPB] Namespace lookup failure, AE_ALREADY_EXISTS (20160831/dsfield-211)
[    0.305986] ACPI Error: Method parse/execution failed [\_SB.PCI0._OSC] (Node ffff88007c89ae10), AE_ALREADY_EXISTS (20160831/psparse-543)
[    0.306026] acpi PNP0A08:00: _OSC failed (AE_ALREADY_EXISTS); disabling ASPM
[    0.306052] acpi PNP0A08:00: [Firmware Info]: MMCONFIG for domain 0000 [bus 00-10] only partially covers this bridge

Are you experiencing any issues with your system?

ACPI (ie power management) can be hit and miss in Linux, depending on manufacturer, some of which don't care much about Linux.


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My wife gets that error on her old, wee i686 Acer Aspire One Netbook running recent (within past two years) kernels, Manjaro or Arch. I haven't tried troubleshooting it, as it otherwise seems to function properly.


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No issues with the system - only this apparently benign ACPI error message at boot-up that I've described above. Thankyou for the links: it seems to be an unresolvable hardware issue, and together with the helpful comment by c00ter about his wife's netbook with the same problem, it appears to be nothing to worry about, or at least one can't do anything about it! So, though noone likes error messages, I'll do my best to ignore it and continue enjoying Manjaro :sunglasses:...

thanks for the reassuring reply about your wife's netbook with the same problem. So, it seems to be a 'harmless error' so I'll do my best to ignore it. Apart from that, everything is working really well on this Samsung netbook.

Thanks again, C00ter :sunglasses:

Take that with a grain of salt. She only watches streaming videos with it (with Chrome, albeit), so that is the full extent of my functionality testing.

@eugen-b, are there any plans on re-building Manajro netbook kernels, or are i686 netbooks too much of a rara avis nowadays?


My wife's Dell Inspiron laptop has a similar error on boot up. There appears to be no system issues once logged in.

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many thanks for the reassurance

I also have similar issue on boot in my toshiba p870 laptop from kernel 4.10 i think, but it don't disturb me.

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This reached EOL quite a while ago, either move to 4.12 or 4.9 LTS, or better would be to install both.

Non LTS kernels have a limited life span and need to be monitored. Next LTS kernel will be 4.14.

Hi, I'm now on kernel 4.13. I mean I have that acpi errors on boot from kernel 4.10.

4.9 should already have some kind of fix

Then, acpica is a constant work in progress, and there are still quite important changes waiting to be merged.
Unless you know how to interpret binary DSDT, I'd be wary of necessarily pointing your finger to it.

Hi. Maybe you can read kernel documentation and learn how to use acpi_osi kernel parameter.
Though it is not obvious, sometimes it can help to solve or at least to silence ACPI boot errors.


If you want a kernel tuned for Intel Atom CPUs then install one from http://repo-ck.com (edited)
I'm using linux-ck-atom on my netbook.
Disclaimer: This is not an official advice. Manjaro only supports (meaning: helps troubleshoot) Manjaro kernels. Other kernels are treated as AUR packages.

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Thank you, @eugen-b! :smiley:


This link doesn't seem to be available - I got this notification when I tried it...

It should be http://repo-ck.com

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