How a New MacBook Pro borked an older iMac’s Bluetooth

I collected my new MacBook Pro yesterday, and within a few hours of starting to use it, my iMac looked to be dying: its Bluetooth had fallen apart, and the only way that I could use its Apple wireless keyboard and Magic Trackpad 2 was to hook them up via USB.

My shiny new MacBook Pro had completely shredded Bluetooth on my iMac. All I could do was turn Bluetooth off on the MacBook Pro and restart the iMac.

Beware: if you’re using a Mac running Sierra 10.12.6 and another running High Sierra 10.13.4 in the same room, they could suffer the same fate.

Let me explain the setup, as this bug may be quite hardware- and macOS-specific.

The iMac:

iMac17,1 (Retina 5K, 27-inch, Late 2015) running macOS 10.12.6;
Apple Magic Keyboard, Magic Trackpad 2;
wired ethernet, AirPort turned off, Bluetooth turned on.

The MacBook Pro:

MacBookPro14,1 (13-inch, 2017, Two Thunderbolt 3 Ports) running macOS 10.13.4;
no attached peripherals;
AirPort turned on and sole network connection, Bluetooth turned on.

No such problems had occurred with a MacBook Air 2011 running 10.13.4 in a similar configuration, and the MacBook Pro apparently connected normally with an iPhone (iOS 11.3).

The MacBook Pro had been collected just a few hours earlier, and had initially been supplied with 10.13.3 installed. At 18:13, it was updated to 10.13.4. Following that upgrade, increasingly frequent problems occurred with the iMac’s Bluetooth: the trackpad and keyboard (which infrequently disconnect and reconnect spontaneously) started to disconnect more frequently, and reconnect more slowly.

After 20:00, the iMac emitted a continuous low tone resembling a static vehicle engine for a period of a minute or two. After that, Bluetooth problems worsened markedly, to the point where both trackpad and keyboard disconnected and couldn’t reconnect. I connected them using their charging leads and regained control of the iMac, and at 20:46 restarted the iMac and turned Bluetooth off on the MacBook Pro. Following that, no further problems were experienced with the iMac.

Logs

In the 18 minutes prior to restarting the iMac, it made 3820 log entries from the com.apple.bluetooth and related subsystems. Over the same period an hour later (when Bluetooth had returned to normal), there were only 476.

Much of the later period of the iMac’s log, before restarting, consisted of the MacBook Pro connecting via Continuity, then disconnecting. Log highlights include the following entries:
20:30:44.924571 WirelessProximity Continuity start advertising with data: Advertising request of type 12, priority 5, UseFG 48 (30.00 ms), data …, connectable 1 20:30:45.024858 IOBluetooth Adding UUID FC049FA3-…-ED2F5ACFD6D2 with services in cache 20:30:45.025521 IOBluetooth Found cache for connected device Howard’s MacBook Pro, uuid FC049FA3-…-ED2F5ACFD6D2 20:30:45.220858 IOBluetooth Primary Service Discovery completed with status: 0x0 20:30:45.532130 WirelessProximity Continuity connect to peer: FC049FA3-…-ED2F5ACFD6D2 20:30:45.532253 wirelessproxd We're already connected to this device FC049FA3-…-ED2F5ACFD6D2. Sending back didConnect again... 20:30:46.930376 WirelessProximity Continuity update advertising with data: Advertising request of type 12, priority 5, UseFG 290 (181.25 ms), data …, connectable 1 20:30:56.570834 WirelessProximity Continuity disconnect from peer: FC049FA3-…-ED2F5ACFD6D2 20:30:56.570990 wirelessproxd Disconnect from FC049FA3-…-ED2F5ACFD6D2 called by client F06AECD1-…-DBBC24A68A89 - process identityservicesd (385) - subscribed characteristics: (null) 20:30:56.570994 wirelessproxd Disconnecting from central FC049FA3-…-ED2F5ACFD6D2 for client F06AECD1-…-DBBC24A68A89 20:30:56.571218 wirelessproxd WPDConnection deallocating 20:30:56.604085 IOBluetooth EVENT: Disconnection Complete: Reason = 22

This cycle was repeated, more or less, every 80 seconds. There were also frequent burst of error messages for BluetoothAudio. At the time that the trackpad and keyboard disconnected, there were many more entries concerning Bluetooth, including the following.

20:45:39.804322 kernel IOBluetoothFamily [[0xC000] OpCode 0xFD4B (Broadcom VSC -- LE Set Extended Advertising Data) from: blued (130) Synchronous status: 0x00 (kIOReturnSuccess) state: 2 (BUSY) timeout: 6543] Bluetooth warning: An HCI Req timeout occurred. 20:45:39.896275 kernel IOBluetoothHostControllerUSBTransport [IOBluetoothHostControllerUSBTransport][ReEnumerateOrReset] -- mBluetoothUSBHostController->reset () error = 0x0000 (kIOReturnSuccess) 20:45:39.938786 wirelessproxd Scanner Central manager is unknown, powered off, unauthorized or not supported (0) - reset connection in progress {} and peripheral connections {()} 20:45:39.940717 Error wirelessproxd CoreBluetooth isn't advertising for this client type

Over the same periods on the MacBook Pro, there were 3511 log entries before turning Bluetooth off, and 1489 afterwards. Here, the cycles of attempts to connect via Continuity were different, and typically followed this sequence of highlights:

20:30:44.955997 WirelessProximity Continuity connect to peer: AFC18B6D-…-022DDC693138 20:30:44.956212 wirelessproxd Connect to AFC18B6D-…-022DDC693138 called by client CAEA0447-…-24A13DA6DD48 - process identityservicesd (275) - options (null) 20:30:44.995308 IOBluetooth This is an (Outgoing) Connection - We are Central/Master 20:30:45.126555 IOBluetooth ***** lePairingCompleted for deviceAddr = 28-f0-76-24-46-35 (name = Howard’s iMac) with status = 0 20:30:45.284304 wirelessproxd Connected to device (Howard’s iMac) with UUID AFC18B6D-…-022DDC693138 and role 0 20:30:45.284450 wirelessproxd Created a connection to peripheral AFC18B6D-…-022DDC693138 for client CAEA0447-…-24A13DA6DD48 20:30:56.657063 IOBluetooth ***** [BluetoothHCIEventNotificationMessage] kBluetoothHCIEventDisconnectionComplete 20:30:56.657081 IOBluetooth EVENT: DisconnectionComplete 20:30:56.657092 IOBluetooth EVENT: Disconnection Complete: Reason = 19 20:30:56.660603 IOBluetooth == IOBluetoothBroadcomSchedulerWorkaround start 20:30:56.661418 IOBluetooth == IOBluetoothBroadcomSchedulerWorkaround end 20:30:56.662743 wirelessproxd Disconnected from peripheral AFC18B6D-…-022DDC693138 with Error: The connection has timed out unexpectedly. 20:30:56.662810 WirelessProximity Continuity peer: AFC18B6D-…-022DDC693138 is disconnected with error: The connection has timed out unexpectedly. - send didDisconnect 20:31:11.665368 WirelessProximity Continuity disconnect from peer: AFC18B6D-…-022DDC693138

Interpretation

What appears to have been happening is that the MacBook Pro was trying to connect with the iMac using Bluetooth, which was succeeding initially. However, with AirPort turned off on the iMac, this connection could not be fully completed. This led to disconnection, and increasing instability in the iMac’s Bluetooth stack. There are longstanding bugs in Bluetooth which have plagued all versions of El Capitan and Sierra.

Eventually, that instability resulted in failure, which disconnected all Bluetooth devices from the iMac.

What are the key requirements for this to happen?

The combination of Sierra and High Sierra 10.13.4,
One system with AirPort turned off, falling short of the requirements for Continuity,
Bluetooth input devices on the system with AirPort turned off.

The two Macs may then enter this cycle of connection and disconnection, eventually leading to failure of control over Bluetooth on the Mac running Sierra with AirPort turned off.

The only solution seems to be to turn Bluetooth off on the other Mac, and restart the affected Mac. Turning AirPort on could also prevent the problem by stopping these connect-disconnect cycles. As far as I can tell, this is a problem introduced with High Sierra 10.13.4 on certain models, such as the MacBook Pro.

If you have suffered similar, I’d be delighted to hear of your experience, please.

8Comments

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1

bcroadtrip2018 on April 13, 2018 at 9:06 pm

I have similar problems running an iMac 21.5″ and a MacBook Pro 15″ but the iMac was purchased in 2015 and the MBP purchased in 2014. I never presumed that it was the MBP causing the problems and then I also had the iMac freeze up on an irregular base when I was running both a foot or two between each. I’m wondering if it might have been the MBP that might have been somehow freezing it up.

Does Apple have a remedy for the Bluetooth even though they should be on separate channels?

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- 2
  
  hoakley on April 13, 2018 at 9:15 pm
  
  The problem is not radio interference, but (in my case at least) these repeated attempts to establish Continuity connections.
  In El Capitan and Sierra, the Bluetooth stack is somewhat fragile, to say the least. It’s generally OK when handling its own wireless peripherals, but here seems to have been overbalanced by a sustained series of attempts by the MacBook Pro to connect to it.
  There are two obvious approaches: ensure that Continuity is fully enabled on all Macs by turning on their WiFi and Bluetooth, which should allow them to hook up and the connection attempts cease, or turn off both WiFi and Bluetooth, which should block any attempts to connect.
  If you’ve got a wired internet connection but need Bluetooth turned on, there isn’t an easy answer.
  I don’t know that Apple has even acknowledged these problems. I don’t recall it acknowledging them in El Capitan or Sierra, although early El Cap was a Bluetooth disaster for many.
  Howard.
  
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3

macForceOne on April 14, 2018 at 7:07 am

Hello Howard,

I think we are in similar scenario, but I have little different configuration. My iMac17,1 is not wire-connected to the ethernet so everything – Bluetooth and AirPort Wi-Fi is On. Same applies to my MacBookPro14,3. But, there was SAME VERSION of macOS High Sierra 10.13.3 on BOTH of them. I’m also experiencing similar issues with Magic Mouse 2 or Magic Trackpad 2 and Magic Keyboard 2. They disconnect from time to time temporarily. Just for couple seconds then they come back again. It’s doesn’t happen too often so I can live with that, it’s just a little annoying.

I had no idea what this could be related to and so far I haven’t studied any logs. Anyway I just wanna let you know, that weird things with Bluetooths probably happening with High Sierra on both machines too. (I haven’t chance to test it with last version 10.13.4 and take a look some logs because I’m out of home for about 2 months, and I’m now just with my MBP so I will see if last update have solved something when I come back.) Regards…

Manoli

LikeLiked by 1 person
- 4
  
  hoakley on April 14, 2018 at 7:22 am
  
  Manoli,
  Thank you. Sporadic Bluetooth disconnect-reconnect has been a ‘feature’ of El Capitan and Sierra, although relatively infrequent with the later releases of Sierra. I live with that.
  What was unusual on this occasion was that these suddenly became a lot worse, making it hard to use the iMac, and then locked both trackpad and keyboard out completely. I think that is attributable to 10.13.4 running on the MacBook Pro, as it does not happen with 10.13.4 running on my old MacBook Air.
  Howard.
  
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  - 5
    
    macForceOne on April 14, 2018 at 7:40 am
    
    Yeah, I don’t know what you mean ‘infrequent’ for me it was happening approximately once every 2 – 3 hrs for maximum 5 sec disconnection time and my keyboard and trackpad fortunately never remained completely locked out.
    
    With latest version of MacBook Pro you are probably right, because as far as I can remember, this never happened to me with my old MBP from 2014 even with High Sierra installed on both machines.
    
    Manoli
    
    LikeLiked by 1 person
6

dysamoria on May 7, 2018 at 11:03 pm

These systems just keep getting more fragile, as Apple refuse to put the necessary development and testing time into any product, prioritizing their ridiculous Wall Street pathology product release cycles.

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7

Edward on August 23, 2018 at 12:24 pm

A bit late to this game, but I also experienced similar issues with my new MacBook Pro, 2018, i9 2.9 GHz, 32GB RAM. My issue is that I run an external USB audio interface for use in Logic Pro. I kept experiencing severe CPU spikes while playing virtual instruments, and that in turn caused the fans to rev up to obscene RPM’s and noise. I would experience a digital audio glitch sound approximately every 5 mins. I checked my console log and found the same error for Bluetooth:
error 11:54:12.842841 -0500 coreaudiod HALS_IOA1Engine.cpp:365:EndWriting: HALS_IOA1Engine::EndWriting: got an error from the kernel trap, Error: 0xE00002EE
error 11:54:14.728842 -0500 wirelessproxd CoreBluetooth isn’t advertising for this client type

So I removed all BT devices in system preferences, and turned BT off. All my issues went away. I did have the Bluetooth PAN as an active device that I removed. That could be causing the connection loop issue between devices. I do have multiple Macs in my home, and iPhones, so everything could be trying to connect with each other. Surprisingly, the best outcome was the CPU spikes and fan issue going away. However the BT is setup in High Sierra, it is v very buggy. Hopefully Mojave addresses this.

LikeLiked by 1 person
- 8
  
  hoakley on August 23, 2018 at 9:12 pm
  
  Thank you.
  It is hard to known in my case whether this was High Sierra or Sierra which was at fault, but I have had no problems since turning Bluetooth off.
  I also haven’t looked at Bluetooth in Mojave yet, but may get a chance in the next week or so.
  Howard.
  
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