What is the specific process that is draining my iPhone's cellular data?
December 30, 2015 2:16 PM   Subscribe

Since late October/early November, my iPhone 6s (128 GB Verizon, not jailbroken) has been ruthlessly leaking cellular data for no obvious reason. After many days of troubleshooting, I narrowed the culprit down to the infuriatingly unspecific "Documents & Data" category in the iOS 9 “Settings/Cellular/System Services” settings. How can I determine specifically what “documents” and/or “data” is causing the data leak?

My wife and I are on a shared 14GB Verizon Wireless plan, and just in the past 7 days, my iPhone has already burned through 5 GB of data, seemingly through no fault of my own. My wife also has an iPhone 6s, but does not have any of the data leakage issues that I am having. The leak is happening via the “Documents and Data” category, so I have no idea what specifically could be causing this problem.

I am very well aware of this long thread on the Apple Discussions site, where other people are reporting the same issue. But none of the mentioned workarounds or fixes work to alleviate the issue for me. Because this is such a difficult problem to replicate in realtime, I want to avoid having to get on the phone with Apple Support to go through all of the stupid newbie tech support troubleshooting procedures that they will invariably have me go through before they even get to the more granular levels of troubleshooting.

Is there some sort of developer-level method (via Xcode or whatever) of seeing what specific processes are accessing cellular data within a certain time-frame? There’s nothing I dread more than having to deal with Apple Support regarding this issue, so if there is any way I can figure out the problem by myself, that would be a more ideal scenario.

Things I have already tried:

• Full, “nuke and pave” restore of iOS 9.2 (restoring “as a new iPhone”, and not restoring from an existing backup)
• Disabled cellular-usage on as many non-essential apps as possible.
• Disabled iCloud Keychain (on my iPhone, as well as all of my other iOS & Mac OS X devices)
• Disabled “Wi-Fi Assist”
• Disabled all iCloud based Mail accounts (in case there may be a “stuck” outgoing email, as mentioned in this YouTube video)
• Completely disabled other iCloud based services (iCloud Drive, Photos, Notes, News, Find My iPhone)
• Created & signed-in with a brand new Apple ID/iCloud account
• Switched all my other iOS & Mac OS X devices to use the new AppleID/iCloud account
• Disabled “Personal Hotspot”
• Disabled Automatic Downloads for Music, Apps, Books & Updates, as well as disabling “Use Cellular Data” in the “iTunes & App Stores” setting
• Disabled Podcasts app (which I don’t use…I use PocketCasts) background refresh & cellular data

Apps/Services which I have not disabled, because they are personally & professionally “mission critical” to me:

• iCloud Contacts sync (updates sent via “Push” schedule)
• iCloud Calendars sync (updates sent via “Push” schedule)
• iCloud Reminders sync (updates sent via “Push” schedule, syncing reminders only 2 weeks back)
• iCloud Backup
• “Share My Location” from my iPhone
• Wallet (for ApplePay…even though I disabled iCloud Keychain, I allowed it to keep my single ApplePay Credit Card in my Wallet)
• Two Google Mail accounts (updates sent via hourly “Fetch” schedule)
• Two Google Calendar accounts (updates sent via hourly “Fetch” schedule)

Interesting, possibly relevant observations:

• When I first noticed this problem back in November, the cellular data leak would actually occur while I was at home, still connected to my Wi-Fi! The leaks generally happened overnight, for some reason, and I suspected iCloud Backup to be the culprit, but disabling it had no effect. The only thing that seemed to fix it was switching to a different Apple ID/iCloud account.

• The cellular data leak now only seems to occur when I physically leave the house, and walk/drive around town. If I disable Wi-Fi while I’m at home, and let the iPhone just use LTE for internet access, the “Documents & Data” usage is very slow, to the point of non-worry for me.

• It’s clear to me that—unless it’s possible for the per-app cellular data usage statistics in the “Cellular” settings to display incorrect information–the problem is NOT due to a specific data-hungry app, because none of the apps for which I do allow cellular-data access are using significant amounts of data, according to their individual statistics. The data leak only seems to be happening in that nebulous “Documents & Data” category.
posted by melorama to Computers & Internet (13 answers total) 5 users marked this as a favorite
Forgot to link to the Apple Discussions thread I mentioned, as well as the YouTube video mentioning "stuck" outgoing email. Damn you, copy & paste!
posted by melorama at 2:45 PM on December 30, 2015

If you want to go hardcore you could create a virtual server in the cloud and install a proxy server with detailed logging enabled. Then set this as the proxy server in your iPhone network settings. When the excesssive data usage happens check the proxy logs to see what requests are getting logged.

This is a lot of effort though and not bullet proof.
posted by duoshao at 3:33 PM on December 30, 2015

Do you have the Facebook app installed?

Serious question. It's known to be an insane battery drain for unknown reasons, and it might be doing the same to your data.
posted by SansPoint at 3:47 PM on December 30, 2015

Maybe Settings : Privacy : Diagnostics & Usage : Don't Send? Seems unlikely, but you didn't try that yet.
posted by ctmf at 4:10 PM on December 30, 2015

Do you use Dropbox or another document backup/syncing app that is allowed to use the network in the background?
posted by eatcake at 4:14 PM on December 30, 2015

Start removing 3rd party apps one at a time.
posted by LoveHam at 4:19 PM on December 30, 2015

For me it was absolutely wifi assist plus my ongoing use of YouTube and Tumblr via cellular. I am on a family plan and before I turned that all off I used 8 out of our 10 gb of shared data just on my own each month. So absurd.
posted by Hermione Granger at 4:36 PM on December 30, 2015 [1 favorite]

The poster has already disabled wifi assist.
posted by desjardins at 5:35 PM on December 30, 2015 [3 favorites]

Based upon what you say here, and my own 6s configuration and low cellular usage (less than 500 MB/month) I wonder if there is something fishy with the first 5 of your mission critical apps. I sync 2 gmail accounts and use wallet but I experience nothing like the usage you report. I have iCloud turned on but not for cell data. I also have share my location turned off but find my phone turned on. My LTE is turned on for data but not voice.
posted by skye.dancer at 5:40 PM on December 30, 2015

You say switching Apple IDs fixes the issue.
Do you have any photos on your phone it's trying to sync with iCloud? Maybe something is hanging there.
Do you have a Mac? Are they trying to sync data with each other via iCloud?
posted by LoveHam at 7:42 PM on December 30, 2015

Loveham: You say switching Apple IDs fixes the issue. Do you have any photos on your phone it's trying to sync with iCloud? Maybe something is hanging there.

To be clear, "switching Apple IDs" does *not* fix my current issue. It only fixed my initial problem a month ago, when I'd get the "Documents & Sync" leak even while connected to Wi-Fi.

But I think you may be onto something regarding iCloud Photos. As a test before leaving the house yesterday (after I posted this question), I completely disabled iCloud Photo Library on my iPhone. Lo and behold, after returning home 2 hours later, my "Documents & Sync" usage was only around 150KB, rather than hundreds of megabytes, like it was earlier in the day.

I have noticed that Photos.app on my Mac will complain about there being "Unreadable Files" when I plug my iPhone in and it tries to auto-import (see this screen grab). When I check the Console log for more details, it looks like some sort of error in the ImageCaptureCore framework.

I'm not sure if this has anything to do with my problem, but it seems all evidence so far points the finger at Photos. I'll keep investigation, thanks for the idea.
posted by melorama at 11:54 AM on December 31, 2015

There is definitely something weird going on with iCloud Photo Library.

Thinking that the Photos database on my iPhone may have been corrupted or something, I deleted all the photos and videos on the phone last night using "Image Capture" on my Mac, then re-enabled iCloud Photo Library again (with Photo Stream & iCloud Photo Sharing disabled, as well as Cellular usage turned off on the Photos app), hopefully to start fresh.

This morning, I left the house for about 2 hours for breakfast, then came home and checked the "Documents & Sync" usage. It was 27.7MB of usage, which seems more than normal, but at least it wasn't something crazy like 400-500 MB like it was a few days ago.

I left the house again this afternoon for about 1 hour, and came home to find that the D&S usage had increased to 191 MB! Not good.

Doing more Googling just now, I found this TidBITS article by Adam Engst, mirroring my own experience with the "Documents and Sync" cellular leak. He mentions that "repairing" the Photos Library on his Mac seemed to alleviate the data leak on his phone (albeit with a painful re-upload of his library back up to iCloud).
posted by melorama at 8:15 PM on January 1, 2016

Late followup...but repairing my Photos library on my Mac, as mentioned in the aforementioned TidBITS article, did not fix the issue, unfortunately.

I guess I'll have to learn to live without using iCloud Photo Library on my iPhone for the time being.
posted by melorama at 1:51 PM on January 13, 2016

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