Connection to the target is possible (SYStem.Up / SYStem.Mode Attach + Break). After resuming the execution (Go), a “debug port fail” error or similar is returned at a later point.

Possible reasons:

• The debug module or JTAG has been disabled by the target software

• The core went in power saving mode

• The core went into a secure/non-secure state or a security configuration may disable debug access.

• The target application has crashed

• Illegal access by the debugger e.g., software breakpoint on illegal address

• For Armv8/Armv9 systems, check whether the execution enters EL3/secure firmware and changes the debug permissions

Possible Solutions:

• Verify if the problem is related to a debugger access, by removing breakpoints and closing all windows that can access the memory on run-time

  • Check SYStem.LOG.List for addresses related to this error

  • Check if MAP.DenyAccess can help to prevent the debugger from doing an illegal access

  • Debug the target application until the point where the connection is lost in order to find the reason of the error

  • Check CDBGPWRUPACK / CSYSPWRUPACK and the corresponding DAPDBGPWRUPREQ / DAPSYSPWRUPREQ