Why does the "Unable to activate eSIM" error appear on iOS?

Common reasons:

1. Invalid or expired activation code; contact customer service to obtain a new one.

2. The device is locked by the operator and cannot use other operators' eSIMs.

3. Unstable network connection; switch to Wi-Fi or mobile data.

4. The eSIM has been activated on another device; delete the eSIM from that device first.