iCal private links not accessible anymore after upgrade to Confluence 8

[Eric Daras]

I recently upgraded a confluence server from v7 to v8.4.0.  Since the migration the iCal private links are not accessible without authentication:

wget https://MYSITE/rest/calendar-services/1.0/calendar/export/subcalendar/private/************************.ics

--2023-07-11 06:20:42--  https://MYSITE/rest/calendar-services/1.0/calendar/export/subcalendar/private/************************.ics

Resolving MYSITE (MYSITE)... 192.168.1.1

Connecting to MYSITE (MYSITE)|192.168.1.1|:443... connected.

HTTP request sent, awaiting response... 401 Unauthorized

 Username/Password Authentication Failed.

Please note that the General Calendar option to restrict access to private iCal link is not set.

[mnd]

I am also experiencing this same issue after upgrading from Confluence 7.13 to 8.3.1.