iPhone connects and disconnects from Mac

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!

Connect your iPhone

Run this command in Terminal and it will fix all your problems - sudo killall -STOP -c usbd

Also go to System Preferences > Network > You will see iPhone USB 1, 2 etc. - Select each one and remove them all by pressing the ( - symbol) in the bottom left corner.

Disconnect and reconnect and this should fix all your issues.

I have had that problem for quite a while. I change some settings following different advices given here and there, which had annoying consequences like Google Maps loosing the navigation option, I used a new USB cable, then finally, I used my brain: if your laptop is fully charged 100% or connected to the charger, the phone will stay connected, if the laptop charge is not enough, the laptop will disconnect your iPhone that will reconnect and get disconnected again and so on, with that annoying sound at each step. So the conclusion is: don't try to charge or connect your phone to your laptop if the battery is not fully charged.

Tried connecting a new iPhone 11 to a Macbook Pro (2015) and had this very frustrating problem. Using a new cable. Tried everything, but this actually worked. Not sure if I will have to do this again when I reboot, but I guess we will see.

As a relatively recent Windows transplant, while this solution works, it does have a very clunky windows-like feel to it. Honestly I thought my days of task killing were over now that I am swimming in the iOS pool. :-(

Lord B,

could you please share with the rest of us - why it seems to be fine now? What did you do to fix it?

(my apologies if you posted it already and I missed it)

Many thanks, have a great day and stay healthy.

Bronco

Dear all, I have had this problem 3 months ago, then I thought I had been clearing it by only using my 2017 MacBook Pro instead of my 2016 MacBook Air, the phenomenon happening on the MacBook Air only. Yesterday I used my MacBook Air again as Nd the bloody on/off triggered again. I collected all the iPhone USB cables in the house and tried them one by one. In my case, it is defining USB cable that’s wrong. Only the most recent ones work properly. I have cut and binned all the defective ones, 6 out of 10 . Hope this helps

Fixes devices connecting and disconnecting rapidly with iTunes

Made the script , just save to desktop

Open Automator ---- Run AppleScript --- Add Script --- Save as application in Desktop

Enter System Preferences ---- Go to User & Groups --- Click on your User ---- Login Items ---- Add The Usb Fix . All Done

------------------------------------------------------------

tell application "Terminal"

do script "sudo killall -STOP -c usbd"

delay 2

do script "Your Mac Password" in front window

delay 1

do script "killall Terminal" in front window

end tell

------------------------------------------------------------

Tutorial:https://www.youtube.com/watch?v=IF3eVmLdqpI

Hope you enjoy it :)

It took a bit more than 51%, but this worked for me. I think I charged it up to 70% on my charger before moving it to my iMac, and that ended the eternal connect/disconnect it had been doing previously when I was plugging it into the iMac. I've seen similar behaviour on my car charger so now my suspicion is that the car charger just doesn't have enough juice for a heavily discharged phone. Interesting. Thanks very much for the helpful comment. 🙂

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??

This was fantastic advice - thank you. I'm a techno-dummy who gets visibly shaken when I'm in the Terminal. Me and code do not jive. This however was easy as pie and worked like a charm. The constant connect/disconnect with my iPhone while it was plugged into the laptop, (coupled with the annoying sound) was making me nuts, (well, more nuts than normal). Thanks again!

I've had this problem several times before as well. After trying the various methods I was surprised too that after sufficiently charging both my iPhone and MacBook (>50%), this problem was solved. No clue why, but it worked!

Buy something other than a Mac. At least that's what I'm planning to do. Something as simple as connecting your phone to your computer, should never be such a big problem. I've tried everything and nothing works. usbd is impossible to kill. killall -stop... in Terminal, none of that works. I'm done with Apple. Overpriced and now as problematic as windows. Game over for me.

Have looked up answers for this for a while now. This would happen using both my apple charging cords. Did not believe such a simple solution could work. WORKED! I'm so grateful for you techies. Thank you

This issue began for me when I plugged in the iPhone and was given the message in iTunes that the laptop needs to update software to be able to connect to the iPhone. During the update I accidentally unplugged my iPhone from my MacBook Pro while the laptop was updating software. I have tried everything listed here in this thread except for the iPhone USB setting because I could not see it in mt network settings. Laptop is a 2015 MacBook Pro running Catalina and iPhone is an 8 Plus running IOS 14.1. I spoke to Apple support and they recommended I re-install Catalina in recovery mode. Before I do that I was hoping there may be another suggestion from the community.

I was having this issue, very frustrating. I have a 5-year old iMax and my iPhone would not stay connected for more than a couple of seconds. After trying everything listed in this thread with no success, I found that if I plug it into the USB on my wired keyboard all problems went away. I am just backing it up so I can get my new iPhone 12 on like, hopefully this issue will go away.