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After signing and upgrading my kernel to 5.15 on Ubuntu Server 20.04, everything boots fine. It drops me into a shell login and after a few moments I'm flooded with this error.

bpfilter: read error 0

Any ideas?

Matt Settlemeyer
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  • How exactly did you update the kernel? – Nmath Nov 05 '21 at 02:01
  • Downloaded from the ppa mainline. Then sudo dpkg -i *.deb – Matt Settlemeyer Nov 05 '21 at 02:03
  • The mainline kernel is not considered stable and should only be used for testing purposes. I suggest that you revert the changes that you made. See: [Ubuntu Wiki Mainline Builds](https://wiki.ubuntu.com/Kernel/MainlineBuilds). If you wish to continue testing an unsupported kernel, please [file a bug report](https://askubuntu.com/questions/5121/how-do-i-report-a-bug) so that developers can identify and fix these issues. – Nmath Nov 05 '21 at 02:34
  • Ok, thanks for the links. – Matt Settlemeyer Nov 05 '21 at 02:50
  • Yes, some are having troubles with bpfilter issues. Myself, I have not been able to re-create the issue. – Doug Smythies Nov 05 '21 at 04:40

1 Answers1

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I have found a workaround to fix this issue. If you disable bpfilter and ufw (Ubuntu firewall) as follows, the dmesg command does not display the error messages (e.g. bpfilter: read error 0).

  1. Edit /etc/modprobe.d/blacklist.conf:

    sudo vi /etc/modprobe.d/blacklist.conf

  2. Add:

    blacklist bpfilter

  3. Save and close vi by pressing: :wq and Enter.

  4. Then run the following commands:

    sudo ufw status 
sudo ufw disable 
sudo ufw status

Some system info:

$ uname -a 
Linux 5.15.2-051502-generic #202111121041 SMP Fri Nov 12 16:26:56 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu 
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.3 LTS"
BeastOfCaerbannog
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user1275872
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