Bluetooth not available - iMac 27 5k 10.11.4

Bluetooth is offline and unavailable. Restart your Mac. If the Bluetooth status doesn’t change, disconnect all USB devices and restart your Mac again. If Bluetooth continues to show as unavailable, you might need to get your Mac serviced

.Using a Bluetooth mouse, keyboard, or trackpad with your Mac - Apple Support

Same issue when mine was delivered last week, also get a flickering issue on loading bar at boot, gets around a third of the way loaded then flicker's on/off a black screen then fully loads. Called Apple and iMac was replaced. New iMac delivered today, working fine until 10.11.4 was installed and now I have the same bluetooth / flickering issues.

For some reason the 10.11.4 can cause the iMac to forget that it has Bluetooth hardware. The same happened to my on my brand new iMac when it updated. To fix this you need to reset the NVRAM by following the instructions here:

How to Reset NVRAM on your Mac - Apple Support

Exactly the same problem here. Brand new iMac, Bluetooth was working fine out of the box initially. But after the upgrade to 10.11.4 Bluetooth is not working anymore. Resetting the NVRAM does not fix the problem.

Any suggestions from anyone?

Thanks!

NVRAM reset worked for me for around 3-4 full shutdowns, then no dice. Had a chat session with Apple yesterday for around an hour. Advised to complete a full re-install of the OS, which I have now done including hard drive format prior to install. Bluetooth been stable for at present 10 full shutdown / clean boots.

However SSD issue still present, after clean install loading bar got to 2/3 before flicker black screen combination. After 2-3rd shutdown / boot, flickering of loading bar had returned to happening after loading a third of the way.

Got another support call scheduled with Apple this afternoon.

Nothing works, I did several NVRAM resets, did a reinstall of OS X (also using Internet Recovery). Still no Bluetooth at all. I am out of options now and I have a support call scheduled with Apple tomorrow. @NDalby, did the support call you had with Apple help you?

Had no further issues with Bluetooth since hard drive format and Internet recovery, although Internet recovery did keep me on 10.11.4 and did not revert me to 10.11.3 as was expected.

SSD hard drive issues still occurring but with no impact to system usage and according to the senior Apple engineer I am dealing with they don't have any precedent for it. Videos x3 made of boot issue and forwarded to Apple along with a system capture dmg for the engineers to look at. Engineer due to touch base with me again on the 13th April but he believe's that the issues are something that will have to be addressed in a forthcoming update.

I had this problem too as did my daughter with an almost identical spec (iMac 27in 5K Retina). These are both brand-new iMacs. I spoke with Apple support today (5th May) who advised it is a known problem with this iMac model. The only solution that works for our two computers is to run the 10.11.4 combo update. This restores bluetooth functionality until you next restart.

Mike

UPDATE: Apple checked the logs from my iMac. It seems my reset of NVRAM did not work, perhaps I didn't wait for the second chime.

They told me to reset NVRAM via the terminal command [sudo nvram -c] and this has fixed the problem.

I hope this helps others.

Mike

I have the similar problem.

iMac 27 late 2015 OS X from 10.11.4 to 10.11.5 latest public beta. Every second computer restart Bletooth is unavailable. Fortunatelly I have standard USB keyboard so I can do reboot from terminal, but it is really disapointing.

Reset NVRAM does not work for me.

It look like problem in driver or firmware of Bluetooth 4.1 module because this issue not occur on iMac 27 late 2013 (Bluetooth 4.0) or mid 2011 (Bluetooth 2.1).

Try sleep you iMac and weak it up again, see if you can get your bluetooth back. It works for me.

You're in a special club consisting all the idiots who bought iMac Retina 5K, 27-inch (late 2015). I went to the Apple Store in London after exhausting all advice in this thread and they gave me a new wireless mouse! Genius? Must be an ironic title? Anyway I am running system 10.11.5 and this is still an issue - no bluetooth, so plugged in an old mouse from previous Mac as a temporary measure (I hope). Apple are however 'Genius' at taking your money.

To all of you (including myself) who have had issues with "Bluetooth Not Available" on brand new 27" Retina 5k i-Macs I have good news. Mac OS Sierra beta 7 (at time of writing) cures the problem totally. I have had 100% success rate in both restart mode and boot from cold mode and Bluetooth is ALWAYS available. I'd love to congratulate Apple but as it's taken such a long time to resolve this problem - I won't. Hopefully the final release of Sierra will not screw things up again

Yes, I have the same issue