1. For microcontrollers without a clock safety mechanism, an incorrect and invalid clock source is set up, resulting in the microcontroller kernel failing to work. This situation is common in Atmega microcontrollers.
2. Mistakenly closing the corresponding programming interface, or multiplexing the programming interface to other functions, resulting in the inability to update the program through this interface again.
3. Misuse of the protection function, resulting in a temporary inability to program. STM8 lock-up is generally this reason, ROP error leads to the programming function is disabled.