[Evolution] Failed to connect calendar “CalDAV : NextCloud"

[Jim Popovitch <jim k4vqc com>]

Hello,

Since NextCloud v18.0.4 release I have been unable to connect Evolution
v3.30.5-1.1 to continuously CalDAV.  I can setup a CalDAV in Evolution,
and Evolution does prompts for the password and can correctly query
NextCloud for available calendars to select, but when the CalDAV
connection is saved, Evolution persists to display a blue banner with:

     Failed to connect calendar “CalDAV : NextCloud"
     Failed with HTTP error 404: Not Found.

NOTE: there is only HTTPS on the NextCloud serve, and NextCloud works
perfectly fine in Firefox.

How can I debug this and/or resolve this?

tia,

-Jim P.