尽管验证成功，但Google日历未在从iCal-URL导入的事件中加载

Question

I am currently facing some problems with exporting data to Google Calender using the "Import URL"-option. My iCal format is the following (i've hidden some of the information for privacy purposes:

BEGIN:VCALENDAR
VERSION:2.0
PRODID:<-//maskedforprivacy//maskedforprivacy//NL>
X-WR-CALNAME: maskedforprivacy
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/Amsterdam
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
DTSTART:19810329T020000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
TZNAME:CEST
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
DTSTART:19961027T030000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
TZNAME:CET
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:20190401T101550-1143242585-maskedforprivacy
DTSTAMP:20190401T101550
DTSTART;TZID=Europe/Amsterdam:20190104T080000
DTEND;TZID=Europe/Amsterdam:20190104T170000
SUMMARY: ZLU 60 jaar - Medewerker op- en afbouw
LOCATION: maskedforprivacy - Europaplein - 
END:VEVENT
BEGIN:VEVENT
UID:20190401T101550-1227247949-maskedforprivacy
DTSTAMP:20190401T101550
DTSTART;TZID=Europe/Amsterdam:20190105T160000
DTEND;TZID=Europe/Amsterdam:20190105T220000
SUMMARY: Nieuwjaarsconcert - Duty Manager
LOCATION: maskedforprivacy - Klinkertstraat - 
END:VEVENT
BEGIN:VEVENT
UID:20190401T101550-698202101-maskedforprivacy
DTSTAMP:20190401T101550
DTSTART;TZID=Europe/Amsterdam:20190206T090000
DTEND;TZID=Europe/Amsterdam:20190206T101500
SUMMARY: Levering maaltijden - Medewerker logistiek
LOCATION: maskedforprivacy - Wiebachstraat - 
END:VEVENT
BEGIN:VEVENT
UID:20190401T101550-549715553-maskedforprivacy
DTSTAMP:20190401T101550
DTSTART;TZID=Europe/Amsterdam:20000101T120000
DTEND;TZID=Europe/Amsterdam:20000101T130000
SUMMARY: Standaard documenten - Partymanager
LOCATION: maskedforprivacy - Klinkertstraat - 
END:VEVENT
END:VCALENDAR

I've tried to export it with and without the following headers:

header("Content-Type: text/calendar");
header("Content-Disposition: inline; filename=EPCalender.ics");

Validiting the format using https://icalendar.org/validator.html#results returns a success without any warnings. Importing the iCal using an URL in Outlook is working perfect. Is there any property I am not setting up correctly for Google Calender to deny importing the events?

Thanks in forward!

Answer 1

1) I use Content-Disposition: attachment; for my subscribable ics urls.
2) Note: "add by url" is a subscription not an import. Import is a once off activity that may work on non pulic urls if one is logged in. For subscribing, the url must be publicly available without being logged in.