The community will undergo maintenance on October 16th at 10:00 PM PDT and will be unavailable for up to one hour.
That seems to be correct. Read here:
https://community.ptc.com/t5/Mathcad-Tips/Official-PTC-Mathcad-15-and-Prime-1-6-End-of-Sale-Announcement/m-p/715416#M131
Success!Luc