I'm getting timeouts on my USB every few seconds like this:

Jan  8 22:07:43 Thorstens-MacBook kernel[0]: USBF:  1722. 27    AppleUSBEHCI[0xffffff800b8b2000]::Found a transaction past the completion deadline on bus 0x24, timing out! (Addr: 6, EP: 1)
Jan  8 22:07:45 Thorstens-MacBook kernel[0]: USBF:  1724. 29    AppleUSBEHCI[0xffffff800b8b2000]::Found a transaction past the completion deadline on bus 0x24, timing out! (Addr: 6, EP: 1)
Jan  8 22:07:52 Thorstens-MacBook kernel[0]: USBF:  1731. 32    AppleUSBEHCI[0xffffff800b8b2000]::Found a transaction past the completion deadline on bus 0x24, timing out! (Addr: 6, EP: 1)

How can I figure out what is going on? Which of my USB devices may be causing this issue (other than disconnecting one after another)? What other ideas are there to avoid this problem? (Note: My USB hub is powered, which was one of the suggestions I had seen when googling the issue).


Here are the devices connected ty my Mac through a powered USB hub:

  • printer (HP Deskjet)
  • iPhone docking station
  • JBL iPod dock/loudspeaker (also powered)
  • a Pinnacle DVB-T antenna
  • a Garmin charger for my GPS watch
  • a Garmin ANT+ connector
  • an (unused) Logitech headset
  • Can you give us a list of the devices that are connected to your computer with USB? Jan 8, 2012 at 21:22
  • edited the question to reflect my devices
    – IronGoofy
    Jan 9, 2012 at 7:37

4 Answers 4


Generate a system report (in Lion: About this Mac-> More Info -> System Report, or do a Spotlight search for System Information if you allow Spotlight to index applications.)

Click on USB; then look for the bus ID mentioned. Under that bus, look through the Location IDs of each device; this field is "Addr" in the error logs. Note that location IDs are unique only across a bus, not the entire system.

Once you've identified the device, I would try swapping it to a new port, either with another device on the hub or to a blank port on said hub. If the errors stay with the device and not the port, my next step would be to plug the device into a direct port or swap cables. If you still have issues with the device, look for firmware updates to the device.

If after troubleshooting the hub is suspect - note that some people have found the power adapters that ship with some cheap USB hubs to be very poor, not capable of delivering anywhere near enough current. http://hackaday.com/2012/01/06/running-the-numbers-on-a-cheap-psu/

I would put the phone and garmin charger directly off the Mac's USB ports; among other things, your mac can supply twice as much current to your phone for charging. See https://support.apple.com/kb/ht4049

  • Thank you very much, this helped me to nail down the device and get rid of the errors. Just the information I was looking for!
    – IronGoofy
    Jan 9, 2012 at 22:37
  • Out of curiosity, what was it? Jan 9, 2012 at 22:39
  • 2
    It was the Garmin ANT stick .. I can only assume that it is polling for some new data and that the case where no new data is found leads to some issues. Removed it, no new errors.
    – IronGoofy
    Jan 9, 2012 at 23:00
  • I found the same this today with mine.
    – cstrat
    Aug 7, 2012 at 4:10
  • It seems that the issue only appears if the USB ANT+ stick is plugged in, and the Garmin ANT agent is running: forums.garmin.com/showthread.php?14436-Ant-Agent-2-1-6-2-Issues/… Dec 6, 2012 at 5:29

I can confirm my Mac's logs are filled with this error.

Take Garmin Ant+ off the Mac and the errors go away.



I had same issue when I try to connect my ExternalHDD to my MacBookPro. That time my HDD is mounted but I it hangs for few seconds after fixed fraction of seconds interval.

So I had then monitored my console logs and ejected by HDD. As soon as it was ejected I noticed that

apcupsd[90]: Communications with UPS lost

above message on my logs. So I went to the Activity Monitor and force quit the "apcupsd" that process as its not necessary to keep it running (Its a APC UPS monitor process) then I had uninstalled that APC Ups app. Dramatically My External HDD starts working fine on reconnect.


Same issue here. Unplugging Garmin ANT+ fixed it.

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