A spot of research can help to solve any number of problems.
In this particular instance the new AAF website was having issues with the newsletter generator. It seems to be crashing when it was trying to manage the subscriber list.
However a quick bug report and a spot of reading of the bug history led me to a solution that, for now, appears to be a suitable workaround for the problem: disable two other components that are shipped by default, and the conflict is gone.
As a bonus I now know who the developers fr this product are and how to get in touch with them…