Why can't Apple official website find the serial number?

If you can't find the serial number, the phone may be a black machine.

The so-called black machine is to sell the old machine that has been replaced by a new machine after sale through some channels (or the motherboard that has been assembled and replaced by yourself). Because this machine has been replaced by a new machine or official machine after sale, the serial number will also be replaced by a new machine, and it is often impossible to find the serial number of the machine or prompt that the serial number has been replaced.

Mobile phone serial number is the common name of IMEI code. The international mobile equipment identification code is an "electronic serial number" consisting of 15 digits, which corresponds to each mobile phone one by one, and the code is unique in the world. After assembly, each mobile phone will be given a unique group number in the world, which will be recorded by the manufacturer from production to factory. IMEI codes are uniformly distributed by GSM (Global Association for Mobile Communications) and authorized by BABT (British Communications Certification Management Committee).