Can I just add - that I ship a large volume of these out to clients, at least 4 have had the same issue with bluetooth breaking after 10.11.4,
Further more I too personally experienced it on my own system this week. Checking console logs it seems the bluetooth kext just download on some boots in 10.11.4 - its definitely a wide spread bug, multiple people with the same issue, and there are many threads online about it. A reboot for me has always got the bluetooth kext to load but its obviously intermittent as some are rebooting many times and seeing no solution. I suspect most of the fixes here aren't' fixes it just happens to be work fine after you've done it for a few more reboots.
I'll be raising a Rdar with Apple about it, wouldn't be surprised if they're not already aware though.
Further more I too personally experienced it on my own system this week. Checking console logs it seems the bluetooth kext just download on some boots in 10.11.4 - its definitely a wide spread bug, multiple people with the same issue, and there are many threads online about it. A reboot for me has always got the bluetooth kext to load but its obviously intermittent as some are rebooting many times and seeing no solution. I suspect most of the fixes here aren't' fixes it just happens to be work fine after you've done it for a few more reboots.
I'll be raising a Rdar with Apple about it, wouldn't be surprised if they're not already aware though.