iPhone connects and disconnects from Mac

For me it was the issue with the iPhone OS. So, I unplugged the USB from mac to phone and I plugged it into a wall socket and I updated my iPhone to the latest version and everything is fine now.. It might not be the same reason for everyone but for one who is running lower version in their mobiles might find this helpful...

I followed the suggestion regarding power. My iPhone x was at 37% and pulled the cable from my Macbook pro, plugged in a powered USB hub, then plugged my iPhone into the hub. No more issues.

It ****** me off that Apple couple not provide an answer about this problem and we had to figure out how to get around it. I wish Tim would stop worrying about promoting his gay agenda and get back to running the business.

I have been having this problem for a loooooooong time. Tried every recommendation I could find, none of them worked, and finally found out about SMC reset which is recommended for port issues in general. This fixed my problem -at least for now-.

http://osxdaily.com/2010/03/24/when-and-how-to-reset-your-mac-system-management-controller-smc/

Spent three days at the Apple store. Finally a tech deleted my phone backups and created a new one and that's all it seemed to take. Maybe it was some other things we'd tried previously, but this seemed to work right away. There seemed to be some conflict with iTunes and Photos bumping into each when I connected. I know it sounds too easy, but give it a try. It worked for me.

If you want a ton of detail, read here: https://apple.stackexchange.com/questions/382002/iphone-mac-connection-issue-and-what-does-the-usbd-process-do But the short answer is that executing "sudo killall -STOP -c usbd" from the terminal app will not require continual force quitting of usbd process. It should last until you reboot your Mac. So far, it's worked for me, but the pitfall is charging occurs at a much slower rate. Good luck!

I have the same issue with an iphone 7 connecting to my MBA. I found that putting the phone in "Low Power Mode" avoids the USB-looping problem, and once the phone is fully charged, it automatically takes itself back out of Low Power mode and is fine. For ease & convenience, I put the "low power mode" icon on my Control Center (the thing where you can turn on/off the "flashlight" and Airplane mode), by going to Settings --> Control Center --> Customize Controls.

This is a workaround, not a long-term fix. But it's a fast & easy one. I suspect the guy mentioning higher current draw during charging a <50%-charge battery is on the right track though. Care to chime in, Apple Support??

I have a friend with a 2013 MBA and this happened some time ago when I was showing her how to back up her phone to the laptop. At that time the solution was to go to Network settings and remove the phone as a network device. Tried to back up her phone again recently, it kept doing the connect/disconnect but it didn’t show as a network device and no other solution worked, including resetting trust on the phone. Her laptop has another account just for backing up her moms phone, and so I had the thought to log into that account. Sure enough the phone asked if I should trust the computer, I said yes, logged back into my friend’s account and the phone then worked fine. So if no other solution has worked, try creating a new account on the machine and see if the device works like that (if not you may have to reset the trust on the phone first). Hope this helps.

sudo killall -STOP -c usbd

This was the only thing that worked for me as well. (iPhone X + MacBook Air)

Killing usbd via Activity Monitor was not enough.

Terminal sudo killall -STOP -c usbd

Worked! 👍🏽

iPhone XS max / iMac (21.5-inch, Late 2013) V 10.14.5 Mohave

Go to Activity Monitor and search for usbd. Force Quit it. That is what really did work.

Same issue. "Activity Monitor > USBD > Quit > Force Quit" worked for me

I use the terminal and run 'sudo killall -STOP -c usbd' - have been using it for 3 years now and works every time for me-so grateful for this post I have it saved as a bookmark

I could fix this after updating my Mac OS to BigSur .. basically I see issue was with iTunes version which got updated along with OS and issue was solved ..

no issue with usb slot or wire or phone…

I used RPMartin's suggestion and it worked instantly. Go to Terminal and type in the following command:

sudo killall -STOP -c usbd

Hit return, and experience the relief!

AMAZING! It worked! the Terminal thing:

sudo killall -STOP -c usbd

worked perfectly!