With Atmel studio 6.0 RTM released, we are informed about a bug that prevents debugging the projects created with older versions. Though the workaround is small but the impact of the error is monstrous to all the existing users. The issue is as follows.
Open a project in Atmel studio 6.0, that was created with older versions (5.0 or 5.1), and has some debug tool already configured (AVR ONE for example). From Debug menu –> select “Start Debugging and Break”. You will get this rather unfamiliar dialog.
This means that, there is a bug in studio that is preventing you from debugging. . To resolve this issue goto Project –> Properties –> Tools –> Once again select the tool from the Drop down menu, Save the project.
Now things will work ok. Have a good time with studio. !!!!