System Workbench for STM32

This worked for me too. I am using a STM32L476G-DISCOVERY Board.

Opened .cproject file in Notepad++
Edited the field "fr.ac6.managedbuild.option.gnu.cross.board" from "32L476GDISCOVERY" --> "STM32L476G-DISCO"
Saved .cproject file

Then it worked properly. Thanks for your help!