Last week I attended ST Seminar for STM32L4. The organizers expected everyone to use IAR toolchain, but I tried System Workbench instead. Overall it worked fine, but a couple of issues did come up:
1 - We were told that we needed to configure the ST-Link to “Connect during Reset”. I could not find a configuration option to set this and System Workbench was unable to connect to the target. I then found that I could use the ST-Link Utility to configure the target. After the connection setting was changed, System Workbench worked fine.
2 - Several times I generated a “Null Pointer Exception” when launching the Debugger. The most common causes were (a) Selecting the Debug widget which tried to repeat the previous launch but that project was now closed, (b) Selecting “Debug Configuration..” and immediately selecting “Cancel” (on a project with no launch configuration), (c) Selecting “Debug Configuration..” and selecting the configuration for a closed project. None of the errors stopped Eclipse, I just had to go back and do exactly what was expected.