SenorAguas
I happened upon your thread because I was having the same problem getting the "can't do that" error message. Operationally it did not cause a problem, it was just annoying getting the error message.
I seem to have resolved my problem by pausing and then stopping.
You may wish to try editing your hal file in the pause section.
Just before you have the statement: net pause-sig halui.program.stop <= and2.0.out,
you may wish to trying adding the statement:net pause-sig halui.program.pause <= and2.0.out
This is what I did and from the limiting testing I did it seemed to stop the "can't do that" error message. I can not give you an explanation why it worked, but there are many things in linuxcnc that I can not explain. It would be a quick test and if it gets rid of the annoying error message then you can move on. Pause the program and then stopping it should not make any difference operationally that I can tell.