JTAG relies on TCK (clock). If your debug probe’s clock is too high (e.g., 10MHz on a long 30cm cable), signal integrity fails, and the IDCODE is corrupted. Reduce TCK to 500kHz or 100kHz in your configuration file.
When the primary flash tool refuses to work, bypass it entirely using a hardware debugger.
Modern IoT devices (Apple MFi, Xbox, PlayStation, medical devices) use Secure Boot. The firmware must be cryptographically signed for that specific device’s unique ID (UID). A mismatch here means the signature verification failed because the firmware was signed for a different device instance, not just a different model.
The error rarely appears out of thin air. It is typically triggered by one of five scenarios.
