Try a different USB cable. Try a different USB port. Reboot. Make sure you are using the ST-Link USB connector if that's what you want to connect to, or the user USB connector with an appropriate program loaded (or the bootloader) if that's what you want to connect to.
"If you feel a post has answered your question, please click ""Accept as Solution""."
Were you able to resolve the issue you described here?
Did you tried @TDK 's suggestion ? Does it work ? If yes, please mark his reply as Best answer (click on "Select as Best").
Imen
In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Thanks