I upgraded the firmware using stlink>upgrade firmware (using cheap stlink v2)
with stm32f103c8t6 connected (boot0 and boot1 are both 0).
After successful upgrade i unplugged and plugged it back and then i can no longer connect to the stm32f103c8t6 using stlink v2
note:below images show the screenshots of my firmware. I can upgrade downgrade firmware but no longer connect and program or read the binary, also the software used is st32 stlink-utility firmware version
UPDATE:I noticed that the problem started when i downloaded a blink program using stmcubemx and keil .The program is working successfully but i cannot reprogram or modify it shows st link usb communication error