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iOS devices connecting and disconnecting rapidly.

I've been having this issue for a while with my iPad Air 2: When I plug it into my MacBook, it will act as though I am plugging it in and unplugging it rapidly, and will not stay connected long enough for me to sync or backup with iTunes.

My iPhone has connected perfectly until today, when it started doing the same thing as the iPad. All other USB devices work fine, and my iPad and iPhone both connect with the windows computers at work just fine. I've tested with both USB ports on my MacBook, and with several known working cords, both Apple branded and not.

I've done a lot of searching, and haven't found any definitive answers or solutions, but today I thought I would try something.

I use Windows 10 in VMWare on my laptop for work (and yes I made sure it wasn't running before trying to sync to make sure that wasn't causing the connectivity issues). But today I opened Windows on my MacBook, and when I plugged in my iPad I told it to open in Windows, and voila it connected to iTunes in windows fine and stayed connected.

This leads me to believe it is some sort of software issue on the MacBook side of things. I even tried closing itunes and just plugging my phone in to charge, and it again acted as though I was continuously plugging it in and unplugging it, but stayed connected in Windows.

Is there something I can do to correct this? I thought it might be an iTunes issue, but since it wouldn't even keep my phone connected enough to charge without iTunes open, I'm assuming it's an OSX issue.

Any suggestions would be greatly appreciated!!

Answered! View the answer I have this problem too

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I had this issue for over a year. Today I stumbled across a page that said to do a SMC reset and now it is all fixed!! Shutdown the Mac and connect the power cable. Hold down Shift+Control+Option+Power all at the same time for a few seconds. The light on the power adapter will blink or change colour once you remove your fingers (all at the same time). When it does this you’ll know ths SMC reset is complete. Turn your MacBook on by hitting the power button like normal. It should be fixed now

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I had this problem connecting two devices at once through a USB hub Now realise it was because the power was coming from a low power wall charger 5v and it was trying to charge the MacBook as well

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I had this problem and solved it by buying a powered USB port that provides external power to the devices that I plug into it. I bought it for CD burners, but now I use it when plugging in my iPad into my Mac

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Tried everything, the only thing that works, is charging my iPhone 11 and 8 to 100%, then the disconnecting solved.

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Tried reset location & privacy. Didn't work. I swap with another cable (also genuine from Apple), problem solved.

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36 Answers

Chosen Solution

You need to reset the privacy settings in IOS, then it will recognised again.

If you have not connected your iPhone to your computer in a while and the computer was updated with new software, there could be some trust settings issues. In order to check and resolve this issue, Open your iPhone, tap on Settings > General > Reset > Reset Location & Privacy.

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solved my problem.

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I have been looking for a solution for this for over a year. Thanks for solving my problem.

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fixed my problems also, thanks been trying to fix this for months

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Did not help... still the same...

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worked like a charm

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Sometimes, the issue is purely a software one. Occasionally, there are problems with usbd daemon programme, which is the root of the issue with the iPhone.

A possible solution to this problem is to open Terminal.app (Applications -> Utilities -> Terminal) and execute the following command: sudo killall usbd . It will kill the programme and it will immediately relaunch. You will need to provide your password. Please note that the password will not be visible, it is normal.

If it does not work, try entering a different command in Terminal: sudo killall -STOP -c usbd . Once more, you may need to present your password

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THANK YOU SO MUCH!! I tried everything else here and this is what finally worked :)

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Bless you! I've had this issue for so long and this finally fixed it. Thanks a bunch! :)

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This fixed mine !!!!!!!

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been trying to fix this for months. this is what worked. thanks!!!

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It works! I did the commands with my iphone plugged in, and it immediately stopped the annoying vibrating, and connected.

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I also had this problem with my iPhone 6 and MacBook Air with an original Apple cable that works fine when charging normally, so it had to be something with the computer.

I chatted with Apple customer support and they told me to update to the newest OS-X and do an SMC reset on my MacBook Air. It’s easily done and did the trick for me. They also told me I could try an NVRAM reset, but this was not needed in my case.

Hope this can help someone!

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it helped me. Thank you so much. I had to update and NVRAM reset

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I was having this problem for more than two years. Finally today, I have updated the latest OSX and then done an NVRAM reset. Cheers, my iPhone is connecting very smoothly with my MAC. Thank you so much.

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Unfortunately I have tired everything, and both these options did not work either.

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the second command with STOP finally resolves the issue. THANKS!

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Worked temporarily, then started it's nonsense again...

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After trying all the recommended fixes for this issue in all the different forums I could find (new cables, privacy setting resets, full system reset etc) I still had the problem so I have come up with a work around.

I now plug all my devices - iPad, iPhone - in to a USB multiport and then connect the multiport’s USB cable to my MacBook air. Problem solved!

I’m using the Belkin 4-Port USB 3.0 Powered Hub! - Which I’ve plugged in to power as well as to my Mac.

Basically, letting the Hub power my devices Vs my Mac.

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THIS!! this is the fix! all the other answers botted me but this truly works my g, this just worked with a standard USB powered hub for me aswell,

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This worked! Ugreen 4 way 2.0 splitter

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This is the answer. Make sure it's a powered USB hub though, because the issue is that the phone is drawing too much power and the laptop 's USB can't handle it for one reason or another.

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In my case I was plugging my iPad on a powered USB so I don't think power was the issue. However the problem was, it's now working properly after using an old usb hub. THANK YOU !

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Mine always does that. I think it's because battery is not charged enough.

I can only connect successfully when my MacBook Air battery is 100% even then it takes a second try :) .

I think it doesn't get enough energy from USB when battery is not charged enough. So it keeps try to get enough voltage and fails. I haven't tried but maybe a shorter cable would fix our issue.

Try when your battery is full. You'll see it connects successfully.

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This also happens when the battery is low and when the Macbook is not connected to it's charger. Try connecting the Macbook to a Charger and then connect the lightning cable. This has helped a lot of times for me.

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I have also found it to help when I've plugged my Mac into the power outlet - but not always. :/

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Worked like a charm (the second command). I had been trying everything for the past couple of days searching for a solution online, but nothing seemed to help. I finally landed on this page and by God's grace came across your posted solution. God bless you; you're an angel. You literally saved my iPhone.

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After a long time with this issue, my conclusions:

  1. some of us are having this issue because of a board design issue, current demand from our USB device(iphone/ipad) is higher than mac USB can provide, as a result the port fails.
  2. You will see this issue more frequantly when your device pulls more current - when it has low battery and tries to quick charge or when you use a high demand devices(ipad/Plus/Max)
  3. when only the SUDO KILL command helps you have the 1 & 2 issues i wrote.

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I had this problem with some iPhones and my 15” MacBook Pro Retina, Mid 2013.

I switched from my normally used Left USB-port to Right USB-Port, now the iPhone keeps connected!

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This worked for my MacBook Pro 15" 2014 running Mojave and iPad Mini 2!

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Didn't expect this to actually work but it did, thanks.

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I have the same problem and had not been able to resolve it.

When I connect the very same iPhone with the same cable, through a USB 3.0 hub connected to the MacBook the iPhone gets connected instantly without any issues.

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Same here, just been trying to search for a solution for years but finally I figured out that that problem doesn’t come out o rarely, with a fully charge battery on Mac and like 100% doesn’t come out using a 3.0 usb hub

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SOLVED.......

This worked thank you!!!

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@James Tompkins, it lets you type the password, it's just NOT shown to you as a security measure. Just type your password completely and press enter

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Well, crap. I switched from my trusty old 15” mid-2012 Macbook Pro to a 15” mid 2015 Pro. I ran into this same infuriating issue with my iPhone XS. I actually have two 15” 2015 Macbook Pros on hand at the moment, and it’s doing it on both. Running the sudo killall -STOP -c usbd command fixes it, until I reboot or wake the computer as others mentioned. Plugging in my 6S Plus is better, it usually works, but still does it occasionally on one of them. You can bet Apple will hear from me…

Update (12/17/2019)

Mine is working now. Apple serviced my mid-2015 15” MacBook Pro, replacing the motherboard and I/O board. (so they said, it still has the same serial number) I did notice one thing before I sent it in. As long as it was running macOS Catalina, I had no issues. Downgrading it to Mojave brought on the issues. Upgrading back to Catalina made it go away. However, it was not strictly software specific. The Genius Bar tech replicated it with ease using a triage drive in store. Once I got the laptop back, I reinstalled Mojave out of curiosity. I was still able to reproduce it a time or two, but it was much more reliable. Now that I’m back on Catalina I have no more issues. I now like this laptop except for the pathetic keyboard feel.

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Having the same issue,during the 14 months of xs max ownership I’ve battled every time to get it to sync to my MacBook 2012 running the latest software,where my wife’s iPhone 7 and three iPads have no issues,I’ve blamed my iPhone thinking the port is blocked with fluff,I’ve blamed cables which some do work better than others,eventually I bought a powered usb hub and it’s sorted,though in the meanwhile I’ve uploaded everything to google drive because I have no faith in my MacBook or Apple anymore

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This one is actually which helped me.

Disconnected iPhone > Fired `sudo killall -STOP -c usbd` in terminal > Reconnected iPhone and it worked :)

I am using MacBook Air (13-inch, 2017)

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You may have a USB port issue. Have you tried the other port as well as a different Lightning cable?

To test the system this device is quite useful: USB Mini Voltmeter

USB Mini Voltmeter Image

Product

USB Mini Voltmeter

$9.99

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If that were the case though, the iPad and iPhone shouldn't connect to Windows being virtualized on the same laptop, correct? They connect and stay connected fine in VMWare, just not when they try connecting through Mac OS. And I specified in my post that I tried both ports and multiple cables.

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The Windows VM is connecting via the Apple driver within MacOS so I can't explain why Windows appears to work from within the VM.

I was trying to eliminate the possible hardware types of issues I more often see which is power issues within the USB port.

So if we assume its not hardware then its software within your system. I was trying not to go down this path as it would require a complete wipe of your drive and re-install the MacOS and then test your iPad/iPhone within iTunes with nothing else running.

Then if this worked slowly re-install your Mac apps (from the Apps Store) then after that re-install your VMWare and Windows (from original source images) testing things as you go. Once you got your apps all loaded run a good Anti-Virus/Malware on your TimeMachine backup to make sure its clean and then restore your stuff.

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I solved that problem by a slightly change cable position .... :)

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yes that's was helpful thank you p

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i kept my phone connected to my mac and turned it off for 5 minutes before turning it back on and it stayed connected!

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If you connect through an Apple USB wired keyboard USB port it works fine!

If you don’t have a USB port in the keyboard you may be try a cheap USB hub.

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WOW. This actually worked for me too! I had an OLD hub lying around... worked first go. Frustrates me that I had to go through everything else, and this ended up being the solution!!

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I had 2 problems.

  1. Your iPad could not be activated because activation server cannot be reached. Try connecting your iPad to iTunes to activate it, or try again in a couple of minutes." "If this problem persists, Apple Support at apple.com/support."
  2. ERROR 9 trying to update or restore it in system restore.

I tried virtually everything to no avail trying to restore an old iPad 2 with both the activation AND error 9 problems. finally i took the advice of using a USB hub AND force terminating usbd before iTunes finally recognized the iPad and starting restoring it.

PHEW.

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Your systems USB port power services is having problems!

This is a common issue in the older Unibody MacBook's & MacBook Pro's with iPads as they need more power than what your system can offer. For iPhones I've seen this before when the systems logic board has issues,

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I was able to solve this same problem with my iPhone 6s by restarting the phone. It was not the solution I was expecting, but after trying different chargers, computers, and USB hubs, this is what ended up working.

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restarting the phone did not help in my case. Neither did the stop command in terminal. My issue first noted after updating to Big Sur and also changing some ram.

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I have the same problem, and had not been able to resolve it. When I connect the very same iPhone, with the same cable, but trough a USB 3.0 hub connected to the Macbook, the iPhone gets instantly connected without any issues.

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When you are running a VM, make sure you have your iPhone connected to your Mac explicitly.

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Same Issue lasted for 2 yrs… No way to solve it but…

When i went to the apple store to change the battery of my mac (15”, mid 2015 ), and they changed all the top case including battery keyboard and touchpad, the issue has gone.

So for the ones that have this problem I suggest to change all the topcase, that include the battery.

Bye!

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Update: Problem re-appeared.

So: Mojave

Same here, just been trying to search for a solution for years but finally I figured out that that problem doesn’t come out o rarely, with a fully charge battery on Mac and like 100% doesn’t come out using a 3.0 usb hub

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I’ve had this issue on both USB ports of my mid-2017 Macbook Air. It usually “settles” after a bit of time but not without much frustration, often when I really need my battery charged (when my iPhone 7 is at 2-3% especially.)

It’s really bothersome, but I’ve just tried resetting the privacy settings and I hope that will help.

I’m also using the original Apple charger included with my phone, so I’m not sure that’s necessarily the culprit.

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Make sure your personal Hotspot is switched off, as i found if my Mac is connected to Wi-Fi this will happen until i switch off Hotspot. Looks like the Wi-Fi and Hotspot are clashing.

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Excellent!

I have had this same issue with iPhone 7s and now with iPhone Xs for years and this has solved the problem!

Thanks !

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This didn't work for me. I've updated everything, but I still have the rapidly connecting/disconnecting issue. Very frustrating!

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Me too! My phone just keeps rapidly connecting/disconnecting so annoying have Have you found a fixed yet@rickmckay65

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I’m trying to run the Kill commands and when I do it says password with a little lock... but it won’t let me type my password? Anyone know how to do this? I can’t plug my new phone into my new MacBook :(

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Mine is the same way. Type the password anyway and hit return. It really is getting your input. I know: crazy.

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I have tried literally everything I read on internet and still couldn’t fix it,

So I turned off my MacBook and turned it back on while iPhone was still plugged in, it connected and stayed connected! When I unplugged it and tried it again it kept doing the same connecting/disconnecting thing.

So I would suggest just restart your MacBook while iPhone is still plugged in USB port and see if it solves the issue.

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For some reason it seems to connect sometimes and stay connected at the most random times… and everything else I use works fine with the port so I know it’s working correctly.. but what you suggested seems like a great idea! I’m going to give that a try.. thanks !

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It’s connecting but once it gets to the Itunes part where it tells me to trust this computer for itunes, the pop-up will not show in my iPhone. I will press continue and wait for my phone to pop-up something but nothing comes up.

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I tried the command: "sudo killall -STOP -c usbd" but when I turn it off or close the mac and connect the iphone again, it happens again. There is no definitive solution? I have a MacBook Pro 2015 and I tried with iPhone XS and iPhone 7 plus.

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It’s hardware issue. There is no way to fix this permanently without fixing underlying issue. Perhaps a hot fix could be writing a script that does it on startup (if you know how to), but I am too lazy to do so, so if you don’t know how to, I suggest googling

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@solsergiani the sudo command just pauses the process until next reboot, so you’ll need to enter it each time you restart your Mac.

I created a little Apple script to run the sudo command but just have the command saved somewhere or just scroll up in your recent terminal commands by pressing the up arrow on your keyboard when in terminal to find the command again.

On a side note, I’ve had my MacBook Pro (11,3) fixed just this morning, I’ve had the IO board and MLB replaced and the same issue still occurs with various iPhone XS’ at the Apple Genius Bar.

Apple phone support will escalate this to their engineers (again), but it’s only affecting certain Macs (possibly just MacBook Pros?) and iPhones (particularly XS). So sounds like there’s a security/software issue if it’s affecting certain Macs/iPhones

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it affects by MacBook Air 2013 and iPhone 6s pair also.

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if sudo commands does not work please try to reset NVRAM

ref: Fix iPhone keeps connecting and disconnecting from Mac

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Hi Ricky

I put the codes in terminal and it fixed the problem with our I phones connecting then not ,

but maybe it’s a coincident a day or 2 later my MacBook Air wouldn’t read my external hard drive Which has never happened, which is now my other problem I’ve done the obvious of trying swapping cords etc etc I have older hard drives that all are read by the computer so maybe this is all just a coincident

Any thoughts or anyone ever come across this ?

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@ad8 Running the sudo command to stop usbd process shouldn't affect non-iOS devices, as the usbd process just configures USB connections for iOS devices. So external drives shouldn't be affected.

If you really worried that it does, you can run the sudo command:

sudo killall -CONT -c usbd

This will restart the usbd process. Alternatively you can just restart your mac and it'll restart the process next time your iOS device is connected.

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I have the same issue when I use a external USB wireless mouse. After I unpluged everything, the iphone stay connected with no problem.

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The USB plug for the mouse is drawing too much power.

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I did two things simultaneously. i did the shutdown, hold power button on for 10 seconds, then wait 4 seconds, then press power on a gain to restart, but I also changed to a non-hubbed USB port ie I directly connected to computer.

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I have noticed that this issue is linked with Charging. When I remove the charger, then there is no disconnection.

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Last line no longer available is one of the errors faced by iPhone users. We have discussed the best-fixing methods for Last line no longer available in 2020.


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May 2 2021

I have same problem, but when I connected an external usb hub and connect my iPhone to the hub, the MacBook automatically detected the iPhone.

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Folks forget all those…. its just the cable… change the cable and it works..

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Everyone here has tried that or we would not be here. Yes, some cables are dodgy and don't work, or are blocked by Apple. But even with a brand new Apple cable, same problem. So you are wrong, it many cases it is software not hardware.

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Don't you think people might have tried that? How stupid do you think we are? Your comment is totally unhelpful.

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Changed phones. Didn’t work. Changed cables. Didn’t work. Did all the☝Sudo kill command —worked for a day. Gonna go get the port fixed.

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In some cases, yes that'll work. But for me and others it wasn't that. I tried multiple cables, and even had an Apple tech replicate it in store with one of his cables.

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well, how about the same cable, two different iphones, iphone 7 works, iphone x doesn't ? tried everything, not even going to mention the same phone worked just fine a few weeks ago. Tried a brand new cable too, forget about it. In fact i tried 3. Together with all the resetting, restarting and so on. I am slowly getting fed up with Apple, my service ran out a few weeks ago and obviously no apple store in my town. Lovely !

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On the mac, go to settings>Network> iphone USB

delete all the “iphone USB” i use to have several ( “iphone usb 2” iphone usb 3”)


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Apple tries to make your products the cheapest as possible for them, this way they undersized the VRM which can’t handle the power hungry from devices which charges with more than 1A.

note that if your phone connects without any trick it’ll charge fast, and if you do the Sudo killall usbd command the phone will charge slowly.. also you can check on the about section the power delivered to the device before and after.

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The VRM's are only used by the CPU to smooth out the power to it. The USB power logic is independent to the CPU.

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@danj So my usb could be messed? What should I do?

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There is two circuits involved: the data side and the power side. I would get a USB power meter like this one USB Mini Voltmeter so you can measure the power draw.

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Rick will be eternally grateful.
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