By the end of June this year, my iPhone running iOS11.4 ran nearly 10G of mobile data during a single day. The log of Shadowrocket(An Network Extension app) revealed that my iPhone kept downloading unknown data from
gateway.icloud.com at the rate of about 200kb/s. I tried switching the iCloud account, but the problem appeared again after a short period of time. I was busy dealing with the exams at the time, so I rejected
gateway.icloud.com in Shadowrocket to stop it from using more data. There was no negative impact on daily use.
After some searching, I found some people who claimed they have encountered a similar problem: https://www.v2ex.com/t/459452. However, their solution of logging out of iCloud on macOS devices did not work for me.
But the trouble didn’t end. Since then, a large number of apps crashes while launching on my iPhone and iPad at a frequency of 2-3 times a week. When the problem occurs, most applications will hang at the Splash Screen and crash after about 10 seconds. Applications that crashed including TIM, Notability and all of the Google apps. WeChat and Apple’s own apps are unaffected. During this time, the phone went hot, and will stuck when entering the iCloud settings. My iPhone runs iOS 11.4 and 12 Public Beta, and iPad running 11.4 and 12 Developer Beta.
December 2020 Update: Some readers found a similar issue on iOS 14, but with different symptoms. See comments for more information.
By summarizing my observation and information collected from the Internet, I sum up the symptoms of this problem as follows:
Running iOS 11.4 or lower
- There is extremely high data consumption in “Documents and Sync” section
- The device continuously downloads unknown data from
Running iOS 12 or higher
- Most 3rd party apps will crash after hanging at splash screen for about 10 seconds.
- Device went hot with higher power consumption
- Device stuck when accessing iCloud-related functions and password auto fill.
I tried rebooting, force rebooting, reinstalling affected apps, upgrading iOS(to iOS 12 beta), logging out and logging back in to iCloud, didn’t work. The iPhone will recover from the problem after a while without taking any actions.