iPhone connects and disconnects from Mac

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.

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'm a a loss for what to do at this point and I'm starting to wonder if it's my Macbook itself that is the problem. I've had this issue for the past 3 years with two separate phones, but the same Macbook.

I'm running a 2015 Macbook Pro with Mojave (had this issue on the previous OS as well). I first noticed the issue with my iPhone XS Max, but didnt't think anything of it as I just charged with wall ports and used Airdrop to transfer things. I now have a new phone and would like to be able to connect it to my Macbook.

I now have an iPhone 12 Max and the same issue is occurring.

None of the current solutions people are suggesting have worked. I've tried all of the following:

• terminal commands
• resetting my SMC
• resetting locations and privacy on my phone
• resetting all settings on my phone
• fully updating my phones.

This is really becoming frustrating...

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'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?

I have an iPhone X and MacBook Air. I have done everything and nothing fixed it. Tried this and seems right. I hope Apple figure it out and fix it in new updates, however, I've seen that people have had this problem from 2013.

Re: Why does my iPad keeps connecting and disconnecting from the new late 2013 iMac

Hey everyone,

I just wanted everyone to have the solution here that way when others experience it, they can hopefully find this solution quickly. Luckily several of you like (MrArifFikri) touched on the solution already, I'll just specify the reason for clarity.

It comes down to power, or more importantly "current". Specifically, with an iPad, USB power consumption is very finicky. So in order for the USB direct connection to your PC, USB hub, or laptop you need to make sure your iPad is charged to over 51%. This will reduce the power draw the iPad will attempt to pull from the USB connection. This should give you flawless charging and syncing capabilities. Now you can sidestep this in some cases by using USB ports on your hub, PC or laptop that are closer to the power supply, or series on the circuit board.

If your iPad is below 51%, you need to use the "cube" or power block that came with your iPad. (The smaller one for your iPhone is not recommended as it lacks the internal transformer that the iPad power block has) The reason for this is that your iPad is attempting to draw too much current from the USB connection through a substrate, i.e. the PC, USB hub or laptop connection. They are only designed to allow a limited amount of current through those connections, thus your iPad continues to "trip" the charging circuit in the device because the power draw is too low.

I hope this helps stop the "doodledee.....deeedledoo" beeping madness you're experiencing! 🙂

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.

Connect your iphone to your Mac.

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

@Apple Please do something about it, I've tried everything other users have mentioned and it still doesn't work as it should (only thing that helped temporarily was going in the Activity monitor and quitting usbd process, but when I unplugged the iPhone and plugged it back in, the same error). I believe that I'm not the only one who is having this issue. Yes I'm using genuine Apple cable and yes I do know that you rather sell more phones than solving this issue which occurs to some users. Do something about it, for your customer's sake!

Hy everyone.

I had same issue on my iphone 6, ios 9.3.2. After searching through the web i found following solution that helped me:

You need to reset your privacy and location info and then trust your iphone with itunes again.

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.

After that your iphone should stop reconnecting repeatedly and start to charging normally.

Thanks for the tip.

However in the above scenario my Macbook was jumping from any desktop i tried to work in back to the desktop where I was running iTunes. By the time I had selected any other app (terminal included) I was thrown back to iTunes because it wanted to show me a message. I never saw this message because it got hidden behind the iTunes window. I only discovered the message after taking a guess at what was going on. So with terminal I would have had no chance to type anything, because as soon as I selected the correct desktop (where I keep terminals assigned) I would not get the time to even select the terminal let alone be able to type something into it. It would be far better if this message (regards trust) was thrown up in the notifications sidebar where it would have less influence on the behaviour of Apple's display manager. But seeing Apple have done nothing to improve the display manager with regard to the reliable positioning of apps on desktops I don't expect a change in this area either - a means to interrupt the display manager when it goes berserk - not even being able to reboot via the applet on the top left of the screen. My only solution was to log in from another computer and reboot.

At this point (remote terminal via SSH) using "sudo killall -STOP -c usbd" would have saved me rebooting.

Try Force Quitting the USBd process on your Mac.

1. Open Activity Monitor on your Mac (in Applications>Utilities)
2. Search in the search bar for USBd
3. Double click on USBd and Quit / Force Quit the process.

Hopefully your phone should then charge normally.

I have no idea what this USBd process is and you try this at your own risk - just saying it worked for me with no problems. The phone charged and sync'd perfectly with itunes afterwards

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.

I've also tried all this, too. Only way I can get it to connect is using the activity monitor workaround.

Plugging my 7plus into this mid 2015 retina Pro, and waiting for it to start its incessant beeping, then opening activity monitor and force quit usbd makes it connect.

but - it doesn't 'properly' connect. phone is charging, but doesn't show up in photos to import. which is what I wanted to to really.

I came across this yesterday with my daughter's 8 month old MacBook Air and iPhone 7. When she plugged it in it constantly connected/disconnected. We tried

• multiple lightning cables
• multiple ports on her MacBook
• her phone charges fine with the same cable when plugged into the wall
• her phone and same cable works fine when plugged into another MacBook Air
• My Galaxy S7 charges ok when connected to her MacBook Air
• My brand new iPad also has the same connection issue when connected to her MacBook
• We then tried a different lightning cable that came with my iPad which appears to be slightly thicker, it charged both the iPad and her iPhone OK on her MacBook!
• I later found that if her phone was charged at 71% any of our lightning cables would charge it, when her phone was at 23% only my iPad cable would charge it.
• The iPad still wouldn't charge with the older lightning cable even when at 81%

So I'm thinking that an iPhone that is "more" flat may draw a higher charging current from the USB port. Not sure if the older cables are slightly worn out/ damaged and cannot provide the current, or there is some other tolerance problem, but a newer cable worked for us. That doesn't really explain why it worked with a low battery percentage on another MacBook though with the original cable. There is something weird going on.