System Workbench for STM32

Thanks Kevin,

I checked version of Workbench and Updated, but it didn't affect.

When I try ur suggestion, "Right click on the project, then choose Debug As > Ac6 STM32 C/C++ Application"
a messagebox is displayed a moment(too quickly closed to recognize what is wrriten). But debug dialog doesn't appear.

Finally, I found a desperate solution.

1. Right click on the other project which can be debugged
2. choose Debug As > Debug Configuration(Debug Configulation Dialog open)
3. Create New Ac6 Configulation
4. Input the elf file path of the project in problem, to C/C++ Application: TextBox
5. Select the project in problem to Project: TextBox

After Do that,
I can debug the project as usual.