Domino is configured to allow remote debugging by notes.ini param:
JavaEnableDebug=1
JavaDebugOptions=transport=dt_socket,server=y,suspend=n,address=8703
Debug is tarted in Domino Designer/Eclipse to debug some XPages code. Debugger attaches to different JVM. As I discovered, it is JVM of AMGR which run Java agent previously. Disconnecting and reconnecting debugger does not help.
Only workaround is to shutdown/restart AMGR to be able to attach to HTTP JVM.
Is it possible to set different ports for AMGR and HTTP debuggers?
I spoke to development about this issue and it is a known issue (to them :) . When the Domino server starts up all JVMs (AMGR / HTTP) will attempt to connect to the port as per the debug settings. So which ever process grabs it first wins.
It is currently under investigation to see if you can have multiple ports (I don't have an SPR yet).
You can try changing the sequence of the SERVERTASKS setting in the notes.ini to launch the HTTP before the AMGR. Otherwise stop both processes and then start the one you want.