A month ago I bought a used phone, before buying the buyer left his account. 2 weeks ago the system update came out, so I decided to update (Now I understand that it would be better not to do it.
The problem is that after the update, the phone asks for the activation code, the activation code is not mine, the Apple ID is also not mine (I don't know what to do).
I hope only for your help and support.
iPhone 7 Plus, iOS 13
You need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/ and erase the device, then remove it from their account. If you can’t do that, the device is useless. Apple won't unlock it.
Activation Lock Problem
If you purchased the device second-hand, then it is useless without the Apple ID and password to which it is locked. If you don't have it, can't remember it or cannot get it, then the device is useless to you. Try to get your money refunded, if you can, or take it to an Apple store for an exchange provided they will help you. If you are the original owner, then take the device, a copy of your purchase receipt and identity proof to an Apple retailer where they may be able to assist you. For a deceased owner see How to request access to a deceased family member's Apple accounts - Apple Support. Note: there is no guarantee that anyone can gain access to the device.
About Activation Lock on your Mac - Apple Support.
Activation Lock - Turn off Find My iPhone.
About Activation Lock on your Apple Watch - Apple Support.
Turn off Activation Lock - Apple Support.
Need to disable Activation Lock on an iPhone or iPad?
When buying came out of iCloud, and now says that the phone does not invite its apple id
Please try restating your last post. Buying out of iCloud? The phone does not invite its apple id?
After the upgrade, the phone asks for activation data not mine
