Shorten your cables, ensure you have a common ground between the programmer and the target, and try lowering the Clock Speed (Frequency) in your programmer settings. 3. Read-Out Protection (ROP)
: Modern USB 3.0/3.1 ports often cause handshaking drops during the firehose sending process. Use a native USB 2.0 port or a USB 2.0 cable if possible. Re-trigger EDL Mode writing flash programmer... fail unlock tool
Which are you using (e.g., Keil, STM32Cube, OpenOCD)? Shorten your cables, ensure you have a common