After fiddling around for a few days, no longer to be able to noratize ;) my applications with the error message given in this thread's title line, now I've noticed what's going wrong:
When you see this err msg in the log (me, using AppWrapper's notarizing tool),
you've to confirm new agreements with both iTunes connect and Apple Developer accounts first at their respective web sites.
You need to check iTunes Connect as well, even if you don't do iOS.
Hope this helps others who fall into despair.