[Evolution] WebCal import fails

[Jay Strict <jay strict posteo de>]

Hello,

I have got a WebCal calendar somewhere on the web and I am trying to add
it to Evolution 3.16.1.

Using New -> Calendar -> On The Web
and typing in the URL seems to work,
but the calendar is not displayed at all in the week view (or any other
view).

Searching through the logs (running with or without WEBCAL_DEBUG=1), I
found the following message repeated very often:

============================== snip ==============================

(evolution-calendar-factory-subprocess:1824): libecalbackendhttp-WARNING
**:  The component does not have the  mandatory property UID

============================== snap ==============================


Any suggestions?

Kind regards,
Jay