Why I have my iPhone 6 restart occasionally with all the app still working?

[Genaold]

Hello,

My iPhone 6 sometimes restarts itself without any reminder or special using, and it's just back to the previous shutdown interface within 3-5s. Do you guys encounter the same problem?

 

[Rob Phillips]

Are you saying that your iPhone restarts and then automatically launches whatever app was previously on the screen? Are you seeing the Apple boot screen when this happens? Is this happening with one particular app or multiple apps?
Without more information I can only recommend restoring, and I always recommend booting into recovery mode and using iTunes. Doing so forces iTunes to install a fresh copy of iOS on your device.
https://support.apple.com/en-us/HT201263

 

[Genaold]

Hi, for your concern, indeed my iPhone 6 restarts and then automatically launches whatever app was previously on the screen, usually several of them and no one lost with the restart action. But nothing special with Apple boot screen, just like a normal restart, but...the thing is I don't give it a reboot order...

PS: I didn't update to newest iOS, just keep 8.1 version, cuz I think its the best to keep the original one, so that there's no app compatibility problem afterwards. Is this the possible reason for the restart phenomenon?

Haven't tried the recovery mode, I'll update the outcome here after done it.

 

[Genaold]

Currently, there's no sudden restart again. But I am not sure whether I found the right way to solve this problem. I'll keep my eye on it to see what will happen in future use.

 

[Ledsteplin]

Currently, there's no sudden restart again. But I am not sure whether I found the right way to solve this problem. I'll keep my eye on it to see what will happen in future use.

You're wrong about the app compatability issue. It's best to keep the phone updated to the current iOS. Apps generally update as well.

 

[Genaold]

You're wrong about the app compatability issue. It's best to keep the phone updated to the current iOS. Apps generally update as well.

Right! I'll take your advice. Thanks, Ledsteplin.