This applies to software devices in general.


For example, with WireGuard...

- if you first don't have the WireGuard kernel module installed
- then create a profile that causes NetworkManager to try to connect (which fails, as the device cannot be created/realized)
- then install the WireGuard kernel module
- then activation of the device still fails



But let's instead reproduce it with bond:


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# ensure you have no NetworkManager connection profiles for bonds

rmmod bonding
echo "blacklist bonding" > /etc/modprobe.d/no-bonding.conf

# verify it works.
modprobe --use-blacklist bonding


# create a profile, which will try to autoconnect...
nmcli connection add type bond con-name b0


# of course, autoconnect failed. Note in the log:
# <warn>  [1551997903.2151] platform-linux: do-add-link[nm-bond/bond]: failure # <error> [1551997903.2152] manager: (b0) couldn't create the device: Failed to create bond interface 'nm-bond' for 'b0': Operation not supported


# now, enable and load the module again

rm -f /etc/modprobe.d/no-bonding.conf
modprobe bonding


# Note that NM fails to activate the profile:

nmcli connection up b0
#Error: Connection activation failed: Failed to find a compatible device for this connection



# note that deleting the bonding profile, and recreating it would succeed to activate it.

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