I'm getting debugging Error "undefined debug reason 8 - target needs reset" with ST-Link V2, BluePill (STM32F103) & STM32CubeIDE, debugger config. is "ST-Link OpenOCD", Although STM32Programmer download & run with same ST-Link V2 without any problem.
Also same STM32CubeIDE debugger is working correctly when BluePill is replaced with H743 Board, here is the result with the BluePill :
Open On-Chip Debugger 0.11.0+dev-00438-ga75fc63 (2021-11-03-15:27)
Licensed under GNU GPL v2
For bug reports, read
http://openocd.org/doc/doxygen/bugs.html
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : STLINK V2J39S7 (API v2) VID:PID 0483:3748
Info : Target voltage: 3.251665
Info : clock speed 5 kHz
Info : stlink_dap_op_connect(connect)
Info : SWD DPIDR 0x2ba01477
Info : STM32F103C8Tx.cpu: Cortex-M3 r2p1 processor detected
Info : STM32F103C8Tx.cpu: target has 6 breakpoints, 4 watchpoints
Info : starting gdb server for STM32F103C8Tx.cpu on 3333
Info : Listening on port 3333 for gdb connections
Info : accepting 'gdb' connection on tcp/3333
Info : device id = 0x20036410
Info : flash size = 64kbytes
undefined debug reason 8 - target needs reset
Warn : keep_alive() was not invoked in the 1000 ms timelimit. GDB alive packet not sent! (1552 ms). Workaround: increase "set remotetimeout" in GDB
O.K.
O.K.:0xE00FFFD0
shutdown command invoked
