You are likely trying to enter fastboot mode via a key combination or ADB without having your device approved through the official "In-Depth Test" (Deep Testing) application.
Are you currently with this error, or are you trying to unlock your bootloader for rooting purposes? Realme C3 problem after unlock bootloader | Early Bird Club You are likely trying to enter fastboot mode
Unlike Google Pixel or Xiaomi devices (which allow fastboot oem unlock with a simple toggle), Oppo—along with Vivo and certain Huawei devices—employs a . This error appears when using the fastboot oem
This error appears when using the fastboot oem unlock command or OPPO’s official Deep Testing / Fastboot unlock protocol. It effectively blocks users from installing custom ROMs, rooting, or modifying system partitions. This article explains why this error occurs, how OPPO’s security model enforces it, and what (if any) solutions exist. The error is not a bug—it is OPPO’s
The error is not a bug—it is OPPO’s secure lock preventing unauthorized bootloader access. It occurs because your device expects a cryptographic token tied to its unique serial number, and none (or a wrong one) was provided.