This error can have several sources:

• The CPU selection in the SYStem window does not match the CPU on the target. Check if the selection matches the processor on the target. Try to use automatic detection (SYStem.DETECT CPU).
• The CPU on the target is not supported by the used debugger software version. Please check if a new version is available in the Downloads section.

In any case please check the AREA window (Menu: View - Message Area) for further information.