Am 14.07.2015 um 12:06 schrieb Eduard Huguet:

A general advice, regarding akmod automatic building: module building
for the kernel just installed is started in background after kernel
update has been completed. This means that, if you restart the system
right after the upgrade process, you might be very well aborting the
module building, thus leading to the frequent problems posted in this list.

Use top, htop or similar after the update to check if the akmod building
has effectively terninated before restarting the system.

why was that behavior changed?

in the past the akmod builds happended *while reboot*
some years ago as i had crap hardware needing that...