iPhone connects and disconnects from Mac

But I do think I solved my problem, by something similar.

On the hunch that the computer was trying to set up a network connection via the phone while the phone was trying to do something else, I went into the network settings and found that in the list of services I had an entry for "Thunderbolt Bridge." I thought it was off, because it was listed as Inactive and the configuration I could see said "Configure IPv4: Off". But to make sure it was really completely disabled I pushed the "Advanced" button to change the configuration details (after clicking the lock icon and authenticating, of course). I changed "Configure IPv6" from "Automatically" to "Manually" and saved that.

After that, connecting my phone to the laptop finally worked. I was just now able to get some pictures off my phone onto the laptop.

I finally figured out the solution to why my iphone kept charging off and on:

I had offloaded / deleted the Music (iTunes) app on my phone. After reinstalling this it allowed me to Trust the computer.

I did what welibelkov suggested:

1. Disconnect your iphone from cable.

2. On your iphone: ->Settings -> General -> Reset -> Reset Location & Privacy (accept all things).

3. Connect your iphone back to cable. (iphone will reconnecting again, don't worry, it will be soon over).

4. iTunes will ask about trust, accept all this.

But was unable to trust the computer cause my Music (itunes app wasnt installed)

Sep 11, 2018 8:27 AM in response to MélodyH

Connect your iphone to your Mac.

Go to Activity Monitor --> Search for usbd --> Force quit it.

The above worked for me. To add a bit: You click on the upper right of your screen where there is a magnifying glass and search "activity monitor." Keep "CPU" highlighted. Type "usbd" into the search box. Now plug in your phone. It'll connect, reconnect, connect, reconnect and so you have to be quick and double click on "usbd" even though photos and itunes keeps popping up. then once you've successfully double clicked "usbd," click on "quit" which takes you to a screen that says "force quit" and click "force quit."

I also took the recommendation of going to my iphone and settings-->general-->reset-->click on reset location and privacy.

I did both and it worked.

I had the same problem. My computer was a late 2014 iMac 27" 5K. Problem started with my iPhone 6 and persisted after I upgraded to iPhone Xs. Things I had tried:

• Restarting many times both iPhone and iMac.
• Changing the USB inlet.
• Using a different USB cable. The problem would stop for a very short time and then return.
• Connecting to my MacBook Pro with the same USB cable. It worked fine. Problem was with iMac.
• Force quitting "usbd" from Activity Monitor.
• Settings>Network> iphone USB> then uncheck the box that says "Disable unless needed"

None of the above worked. Until I contacted Apple Support today. They prompted me to enter this Terminal code:

sudo killall -STOP -c usbd

Problem stopped immediately. I restarted the iMac and things still work fine. Haven't seen how it turns out long-term, though. Give it a try.

This is a cool trick, when your iPhone can’t connect to Xcode (connects/disconnects in a loop):

Sep 11, 2018 8:27 AM in response to MélodyH

Connect your iphone to your Mac.

Go to Activity Monitor --> Search for usbd --> Force quit it.

I have a similar issue and believe it's a power issue.

When I plug my iPhone XR to my 2015 MBP 15 via a USB cable, it keeps disconnecting and connecting. Doesn't happen on any of my MacBook Airs with the same cable, only my MBP 15.

My imperfect solution is to:

1. Make sure the mac accepts the phone: on iPhone Settings -> General -> Reset -> Reset Location & Privacy (accept all things).
2. Plug the iPhone through an external USB hub that uses external power supply (mine is the TB display)
3. On phone, trust the mac connection

Now I can transfer / sync my phone with my mac.

This was one of my struggles and I searched several times for an answer. One comment was finally correct! It’s because the battery is too low! If my phone was under 50% then it would essentially freak out and keep connecting and disconnecting instantly. I think it’s because it was struggling to charge and connect to the iMac. So after it’s charged to a good amount, mine does not do it anymore. I hope this helps other frustrated people solve it. 🤞🏻❤️

I FIGURED IT OUT - so I have a 2015 MacBook Pro and an iPhone 11 Pro Max. Both USB ports gave me the rapid disconnect/connect, and was so frustrating. Tried EVERYTHING - reformat everything, reset everything, BUY A NEW IPHONE, yet nothing worked. THen work gave me a new iPhone SE and it didn't have an issue.

So I thought, maybe it's to do with the power draw/output on the USB port vs a powerful iPhone!

So I got a Ethernet USB adapter that has a USB port on it, and plugged my iPhone it that way.

IT WORKED - no more rapid disconnecting! So it's not an elegant solution because Apple are Apple and we love dongles. But at least I can finally backup and sync my iPhone!

Next problem to sort out: Album Art and songs repeating the last 30s!

This worked for me (going to network in system preferences on computer, click on iphone usb, uncheck box that says disable when needed) when nothing else did. iphone xs max with ios 15 connected to 2015 macbook pro 15 inch running big sur 11.5.1

For the last year nothing else corrected the rapid on/off when phone was connected via usb to computer. This fixed it.

This is a notorious issue. I have faced it multiple times on my iPhone.

Troubleshooting steps range from killing a Mac process to resetting your iPhone. Faulty cables and lightning port could be the culprit.

I found success after following the below steps- 

1. Check cables and ports. 
2. Reset iPhone Location & Privacy Settings.
3. Change Finder Preferences.
4. Restart the USBD process by heading over to Activity Monitor (This fixed iPhone disconnected with Mac issue for me.)
5. Reset SMC/NVRAM on Mac. 
6. Create a new admin account on Mac. 

Let me know if you were able to fix this issue. 

In depth information:- iPhone keeps disconnecting from Mac? 7 Fixes

I had my iPhone doing the same thing, connects and disconnects from Mac, I tried all options mentioned in the forum without lack. Recently I have moved my office to another room and had shut down Mac and disconnect all cables from it, left it off overnight without any cables connected to the Mac, even power cable disconnected from the wall outlet. The next day reconnected all cables and now my phone charges with no problems. I had to Trust my device first.

I'm having this problem too, on an iPhone 7 connecting to a MacBook Pro, both with all software updates installed.

One thing I notice is that the phone very quickly flashes a pop-up ("modal") asking if I should trust this computer or not. But it's gone before I have a chance to press "Yes". (Actually, I once got it in time, and a screen for me to enter my PIN appeared, but only for a microsecond.) The connect/disconnect also stops briefly when the laptop pops up that "A new network interface has been detected: the 'iPhone USB' network interface has not been set up. To set up this interface use Network Preferences". But no matter what I do next, the cycle starts again.

The phone connects correctly to an older iMac running 10.7.5, so I suspect the issue is with the software on the laptop, but perhaps is a cycle of each wanting to verify that I should trust the other and getting in each other's way?

Connect your iphone to your Mac.

Go to Activity Monitor --> Search for usbd --> Force quit it.

sudo killall -STOP -c usbd

That's worked for me!

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...