iTunes and XCode not recognising devices after disconnected, until restart I have a problem which requires I regularly restart my iMac, up to several times a day, to get devices recognized.

When I re-connect a device, iPhone, iPad or iPod, I regularly get the message:

iTunes could not connect to this iPhone. This device is no longer connected.

They no longer show up as active devices in XCode.

When I plug a phone in, it asks me to confirm it should Trust this Computer but that doesn't make any difference.

Note that this is on re-connection. The devices are fine up until the point when I disconnect them. That doesn't change whether I "eject" them from iTunes or not.

Modal nature of problem

It seems that after this problem has started occurring, plugging any new devices in suffers a similar problem.

The problem survived a system restore from backup, which returned some 50GB of space to me. It originally showed up in Mavericks and I have since done an in-place upgrade to Yosemite. It's a mid-2011 iMac 21.5" with four USB ports.

The problem occurs regardless of whether the devices are connected directly into a USB port on the iMac or via the keyboard's extra ports. The devices are all getting power and show up on the System Report as being connected, eg:

USB2.0 Hub:

  Product ID:   0x0608
  Vendor ID:    0x05e3  (Genesys Logic, Inc.)
  Version:  77.60
  Speed:    Up to 480 Mb/sec
  Location ID:  0xfd140000 / 6
  Current Available (mA):   500
  Current Required (mA):    100

iPhone:

  Product ID:   0x12a8
  Vendor ID:    0x05ac  (Apple Inc.)
  Version:  7.01
  Serial Number:    52c05c8223d3efc793f2815e9d3dbcc018805880
  Speed:    Up to 480 Mb/sec
  Manufacturer: Apple Inc.
  Location ID:  0xfd143000 / 10
  Current Available (mA):   500
  Current Required (mA):    500
Using the following in Terminal is an alternative to resting your Mac.

sudo launchctl stop com.apple.usbmuxd


You still have to quit and relaunch iTunes or Xcode in order to see the device.