syslog flooded with "Error do-add-ip6-address" "faiilure 95" despite sysctl disabled ipv6

[Alexander M]

I find my syslog flooded with those message

`Jul 31 09:26:51 thinkbox NetworkManager[469]: <warn> [1659252411.4079] ipv6ll[f07ff1ed609280a9,ifindex=3]: changed: no IPv6 link local address to retry after Duplicate Addre
ss Detection failures (back off)
Jul 31 09:27:01 thinkbox NetworkManager[469]: <warn> [1659252421.4094] platform-linux: do-add-ip6-address[3: fe80::ecec:a4fd:3aae:c6a0]: failure 95 (Operation not supported)
Jul 31 09:27:03 thinkbox NetworkManager[469]: <warn> [1659252423.4109] platform-linux: do-add-ip6-address[3: fe80::55ff:7f77:6b7e:1fa4]: failure 95 (Operation not supported)
Jul 31 09:27:05 thinkbox NetworkManager[469]: <warn> [1659252425.4140] platform-linux: do-add-ip6-address[3: fe80::3b33:a2a2:2287:b08b]: failure 95 (Operation not supported)
Jul 31 09:27:07 thinkbox NetworkManager[469]: <warn> [1659252427.4154] platform-linux: do-add-ip6-address[3: fe80::8656:3f2a:bba6:ab08]: failure 95 (Operation not supported)
Jul 31 09:27:09 thinkbox NetworkManager[469]: <warn> [1659252429.4185] platform-linux: do-add-ip6-address[3: fe80::2066:f2e7:db8a:460b]: failure 95 (Operation not supported)
Jul 31 09:27:11 thinkbox NetworkManager[469]: <warn> [1659252431.4210] platform-linux: do-add-ip6-address[3: fe80::6e7d:ede7:fac0:a6e3]: failure 95 (Operation not supported)
J`

which is odd provided that
a) I have used sysctl to disable ipv6 on all device
b) via linux command line ipv6 is also disabled
c) the loopback device `lo reported in the `failure 95` is not even reported to be managed by NetworkManager nmcli
`DEVICE TYPE STATE CONNECTION
wlan0 wifi connected malware_5G
p2p-dev-wlan0 wifi-p2p disconnected --
eth0 ethernet unmanaged --
lo loopback unmanaged
`

[Alexander M (make-simpler-software)]

fixed incorrect Project assignment

[Javiar C (jchamp)]

Upgraded to Ubuntu 22 from 20, disabled ipv6, similar log file flood:

sysctl -w net.ipv6.conf.all.disable_ipv6=1

Sep 29 12:48:36 srv NetworkManager[663]: <warn> [1664480916.5924] platform-linux: do-add-ip6-address[2: fe80::adf1:51d0:38ef:c006]: failure 13 (Permission denied)
Sep 29 12:48:38 srv NetworkManager[663]: <warn> [1664480918.5949] platform-linux: do-add-ip6-address[2: fe80::4972:49dc:5b46:4b9e]: failure 13 (Permission denied)
Sep 29 12:48:40 srv NetworkManager[663]: <warn> [1664480920.5974] platform-linux: do-add-ip6-address[2: fe80::1588:e1f5:b91d:6585]: failure 13 (Permission denied)
Sep 29 12:48:42 srv NetworkManager[663]: <warn> [1664480922.5998] platform-linux: do-add-ip6-address[2: fe80::cc8e:c60b:a398:cfd7]: failure 13 (Permission denied)
Sep 29 12:48:44 srv NetworkManager[663]: <warn> [1664480924.6023] platform-linux: do-add-ip6-address[2: fe80::7123:5dfa:db2d:8fe3]: failure 13 (Permission denied)
Sep 29 12:48:46 srv NetworkManager[663]: <warn> [1664480926.6037] platform-linux: do-add-ip6-address[2: fe80::525:da2:463b:6812]: failure 13 (Permission denied)
Sep 29 12:48:48 srv NetworkManager[663]: <warn> [1664480928.6051] ipv6ll[ea9e44a59a9d45e5,ifindex=2]: changed: no IPv6 link local address to retry after Duplicate Address Detection failures (back off)
Sep 29 12:48:58 srv NetworkManager[663]: <warn> [1664480938.6088] platform-linux: do-add-ip6-address[2: fe80::adf1:51d0:38ef:c006]: failure 13 (Permission denied)
Sep 29 12:49:00 srv NetworkManager[663]: <warn> [1664480940.6112] platform-linux: do-add-ip6-address[2: fe80::4972:49dc:5b46:4b9e]: failure 13 (Permission denied)
Sep 29 12:49:02 srv NetworkManager[663]: <warn> [1664480942.6133] platform-linux: do-add-ip6-address[2: fe80::1588:e1f5:b91d:6585]: failure 13 (Permission denied)
Sep 29 12:49:04 srv NetworkManager[663]: <warn> [1664480944.6157] platform-linux: do-add-ip6-address[2: fe80::cc8e:c60b:a398:cfd7]: failure 13 (Permission denied)
Sep 29 12:49:06 srv NetworkManager[663]: <warn> [1664480946.6173] platform-linux: do-add-ip6-address[2: fe80::7123:5dfa:db2d:8fe3]: failure 13 (Permission denied)
Sep 29 12:49:08 srv NetworkManager[663]: <warn> [1664480948.6189] platform-linux: do-add-ip6-address[2: fe80::525:da2:463b:6812]: failure 13 (Permission denied)
Sep 29 12:49:10 srv NetworkManager[663]: <warn> [1664480950.6211] ipv6ll[ea9e44a59a9d45e5,ifindex=2]: changed: no IPv6 link local address to retry after Duplicate Address Detection failures (back off)

[James Paton-Smith (jamesps)]

I just noticed this exact same error on my own machine starting 21/11/2022
Many many log entries identical for this are constantly generated.

I checked to see what was most recently updated/installed and I've copied the apt history entry below:

Start-Date: 2022-11-18 15:52:59
Commandline: apt full-upgrade
Requested-By: jamesps (8046)
Upgrade: openvpn:amd64 (2.5.5-1ubuntu3, 2.5.5-1ubuntu3.1), libgdk-pixbuf2.0-bin:amd64 (2.42.8+dfsg-1ubuntu0.1, 2.42.8+dfsg-1ubuntu0.2), gir1.2-gdkpixbuf-2.0:amd64 (2.42.8+dfsg-1ubuntu0.1, 2.42.8+dfsg-1ubuntu0.2), gir1.2-gnomedesktop-3.0:amd64 (42.4-0ubuntu1, 42.5-0ubuntu1), libgdk-pixbuf-2.0-0:amd64 (2.42.8+dfsg-1ubuntu0.1, 2.42.8+dfsg-1ubuntu0.2), fonts-opensymbol:amd64 (2:102.12+LibO7.3.6-0ubuntu0.22.04.2, 2:102.12+LibO7.3.7-0ubuntu0.22.04.1), grub-efi-amd64:amd64 (2.06-2ubuntu7, 2.06-2ubuntu10), libgnome-desktop-3-19:amd64 (42.4-0ubuntu1, 42.5-0ubuntu1), gnome-desktop3-data:amd64 (42.4-0ubuntu1, 42.5-0ubuntu1), grub-efi-amd64-signed:amd64 (1.180+2.06-2ubuntu7, 1.182~22.04.1+2.06-2ubuntu10), grub-efi-amd64-bin:amd64 (2.06-2ubuntu7, 2.06-2ubuntu10), netplan.io:amd64 (0.104-0ubuntu2.1, 0.105-0ubuntu2~22.04.1), libnetplan0:amd64 (0.104-0ubuntu2.1, 0.105-0ubuntu2~22.04.1), libgdk-pixbuf2.0-common:amd64 (2.42.8+dfsg-1ubuntu0.1, 2.42.8+dfsg-1ubuntu0.2)
End-Date: 2022-11-18 15:53:12

Maybe netplan.io could have caused this?

[P.Constantine (pconstantine)]

Can be temporarily disabled by: nmcli d modify <device_name> ipv6.method "disabled"
Annoying ASF

[Dimitri Papadopoulos (dimitri-papadopoulos)]

Same here on Ubuntu 22.04 with IPv6 disabled.

Disabling IPv6 in all devices managed by NetworkManager does help, but I had to restart all connections to stop the error messages. Perhaps Network Manager should not create new connections with IPv6 enabled if IPv6 is disabled in the kernel.

See also:
https://access.redhat.com/solutions/6967304