Comment 3 for bug 829916

The message that you get is just from the driver which binds to the modem after the mode switch.
It seems that this mode switch is not triggered during boot.

This is the second report of that behaviour I get; unfortunately I can't "re-enact" it on any of my systems.

To state it clearly: there was no change in usb_modeswitch which might cause a differing boot behaviour. I tend to assume that there are differences between versions of udev that are game-changing.

As a first try, edit the file /lib/udev/rules.d/40-usb_modeswitch.rules and change this line:

ACTION!="add", GOTO="modeswitch_rules_end"

to this:

ACTION!="add|change", GOTO="modeswitch_rules_end"

This has reportedly worked on ArchLinux. If you don't get results, you might have to activate udev debug logging. More later.