Trouble launching debugger after upgrade to Eclipse 2020-3
I don’t think your issue is because of the tool version.
It looks like the debugger can’t communicate with your board. There is a ST tool (STM32 STLink Utilities) to check if your machine can connect to the board : https://www.st.com/en/development-tools/stsw-link004.html.
Also verify that the switch on your board are connected to use the ST-Link and every drivers are well-installed on your machine.
Regards.