Dear Maintainer,

booting is slowed down by failing ifupdown_pre.service. The problem is
around since a few days only.

[FAILED] Failed to start Helper to …chronize boot up for ifupdown.
See 'systemctl status ifupdown-pre.service' for details.
[DEPEND] Dependency failed for Raise network interfaces.

● ifupdown-pre.service - Helper to synchronize boot up for ifupdown
   Loaded: loaded (/lib/systemd/system/ifupdown-pre.service; static;
vendor pres
   Active: failed (Result: exit-code) since Thu 2020-05-07 22:01:37
CEST; 3min 1
  Process: 269 ExecStart=/bin/sh -c if [ "$CONFIGURE_INTERFACES" != "no"
] && [
 Main PID: 269 (code=exited, status=1/FAILURE)

Feb 14 11:12:00 server systemd[1]: Starting Helper to synchronize boot up fo
May 07 22:01:37 server systemd[1]: ifupdown-pre.service: Main process exited
May 07 22:01:37 server systemd[1]: ifupdown-pre.service: Failed with result
May 07 22:01:37 server systemd[1]: Failed to start Helper to synchronize boo

My system is booted via iSCSI. So the only available network interface
is needed before the init process starts.

/etc/network/interfaces.d/eth0:
»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»
auto eth0
iface eth0 inet static
    address 192.168.0.8
    netmask 255.255.255.0
    gateway 192.168.0.1

auto eth0:1
iface eth0:1 inet dhcp
«««««««««««««««««««««««««««««««

Best regards

Heinrich Schuchardt
--- /etc/network/interfaces.d/*:
auto eth0
iface eth0 inet static
    address 192.168.123.28
    netmask 255.255.255.0
    gateway 192.168.123.254

auto eth0:1
iface eth0:1 inet dhcp

--- up and down scripts installed:
/etc/network/if-down.d:
total 4
-rwxr-xr-x 1 root root 919 Sep 16  2018 sendmail

/etc/network/if-post-down.d:
total 4
-rwxr-xr-x 1 root root 919 Sep 16  2018 sendmail

/etc/network/if-pre-up.d:
total 0

/etc/network/if-up.d:
total 4
-rwxr-xr-x 1 root root 1714 Sep 16  2018 sendmail

Hello,

I hit the same bug on a freshly installed Debian Buster system. It's a server
system with two NICs (eno1 + eno2) but only eno1 has a link. My interface config
is to have a bridge br0 started with eno1 as only bridge port.

Additionally, eno1 is started with an IP during initramfs in order to allow
remote LUKS unlocking by setting the `ip` kernel boot parameter. Maybe that's
related.

In my case, the failing `ifupdown-pre.service` results in the interface `br0`
not being brought up at all, leading to no network after boot.

The best workaround I found was to mask `ifupdown-pre.service`:

# systemctl mask ifupdown-pre.service

Afterwards, the system boots up without delay and interface `br0` is brought up
at boot.

Cheers
 jonas
--- /etc/network/interfaces.d/*:
# WAN bridge
auto br0
iface br0 inet static
        bridge_ports eno1
        # disable spanning tree protocol
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0
        address 172.16.42.10/24
        gateway 172.16.42.1

--- up and down scripts installed:
/etc/network/if-down.d:
total 0

/etc/network/if-post-down.d:
total 0
lrwxrwxrwx 1 root root   29 Jan 28  2019 bridge -> /lib/bridge-utils/ifupdown.sh

/etc/network/if-pre-up.d:
total 0
lrwxrwxrwx 1 root root   29 Jan 28  2019 bridge -> /lib/bridge-utils/ifupdown.sh

/etc/network/if-up.d:
total 0

Dear Maintainer,

This is my first bug report -- but am a 20 year Linux user and hope I
am doing it right.  My main point is that this bug persists in 0.8.37
and the "important" severity is justified.  The effect of this bug for
those of us who still use /etc/network/interfaces to wrest control from
NetworkManager is to make this impossible.  So one workaround that
I tested is to use NetworkManager, unpleasant as it is, to configure interfaces.
The other successful workaround (my preference) is that suggested by Jonas Meurer.

"systemctl mask ifupdown-pre.service".
============================================
Let me add the output of
"systemctl status ifupdown-pre.service"
This occurs before it is masked, obviously, and also when the interfaces
have not been defined in network manager (but do exist in /etc/network/interfaces)

● ifupdown-pre.service - Helper to synchronize boot up for ifupdown
     Loaded: loaded (/lib/systemd/system/ifupdown-pre.service; static)
     Active: failed (Result: exit-code) since Mon 2022-08-08 11:25:14 MDT; 1min 15s ago
    Process: 354 ExecStart=/bin/sh -c if [ "$CONFIGURE_INTERFACES" != "no" ] && [ -n "$(ifquery --read-environment --list --exclude=lo)" ] && [ -x /bin/udevadm ]; then udevadm settle; fi (code=exited, status=1/FAILURE)
   Main PID: 354 (code=exited, status=1/FAILURE)
        CPU: 4.226s

Aug 08 11:25:14 feynman systemd[1]: ifupdown-pre.service: Main process exited, code=exited, status=1/FAILURE
Aug 08 11:25:14 feynman systemd[1]: ifupdown-pre.service: Failed with result 'exit-code'.
Aug 08 11:25:14 feynman systemd[1]: Failed to start Helper to synchronize boot up for ifupdown.
Aug 08 11:25:14 feynman systemd[1]: ifupdown-pre.service: Consumed 4.226s CPU time.

More background:

I have used Debian etch/stretch/jessie and I just upgraded to bullseye
and hit this problem.  I am fortunate to have fixed/wired IP addresses which
I configure via /etc/network/interfaces (shown below).
Note that the error occurs both with the old names "eth0", "eth1"
and the "predictable names"  enp1s0, enp2s10.  (I switched back to eth0/eth1
because I thought perhaps the interface names hadn't been assigned yet
and that is why the network/interfaces file didn't work.)  Regardless,
this bug does not seem to be affected by the interface naming convention
used.

Clearly, noobs who use NetworkManager and DHCP and pointy clicky things to configure their interface are well taken careof.  This bug is freaking out
the old farts though.  I thought perhaps support for the interfaces file
had been dropped entirely ... but clearly not.
--- up and down scripts installed:
/etc/network/if-down.d:
total 8
-rwxr-xr-x 1 root root 1015 Feb  6  2021 avahi-autoipd
-rwxr-xr-x 1 root root  372 May 14  2021 openvpn
lrwxrwxrwx 1 root root   32 Feb 25  2021 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-post-down.d:
total 4
-rwxr-xr-x 1 root root 1409 Mar  7  2020 wireless-tools
lrwxrwxrwx 1 root root   32 Feb 25  2021 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-pre-up.d:
total 8
-rwxr-xr-x 1 root root 4191 Mar  7  2020 wireless-tools
lrwxrwxrwx 1 root root   32 Feb 25  2021 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh

/etc/network/if-up.d:
total 8
-rwxr-xr-x 1 root root 923 Feb  6  2021 avahi-autoipd
-rwxr-xr-x 1 root root 385 May 14  2021 openvpn
lrwxrwxrwx 1 root root  32 Feb 25  2021 wpasupplicant -> ../../wpa_supplicant/ifupdown.sh