'Singlefile'-storage does not sync (upload) to 'caldav'-storage (radicale).

[chr-x]

'Simple calendar' on a Lineage OS phone is syncing via 'DAVx5' (4.4.4-ose) to 'radicale' (3.4.0) webdav server. I want to use 'orage' (4.18.0) on a Debian PC for editing. Read only modus is working fine. Syncing 'orage'-calendar ('singlefile'-storage) to the 'radicale' webdav server ('caldav'-storage) with vdirsyncer (0.19.2 and 0.19.3) fails.

The error messages, one for each VEVENT.

$ vdirsyncer  sync
...
Copying (updating) item 4784a0b4-44c7-487f-b1b1-773b8a42d6fa to col1_remote
error: Unknown error occurred for col1: 400, message='Bad Request', url=URL('https://caldav.at.home:5232/chr/col1/4784a0b4-44c7-487f-b1b1-773b8a42d6fa.ics')
error: Use `-vdebug` to see the full traceback.

radicale.log

...
2025-01-20 21:36:01,576 - WARNING: Bad PUT request on '/chr/col1/4784a0b4-44c7-487f-b1b1-773b8a42d6fa.ics' (prepare): Failed to serialize item None from 'chr/col1': 'VCALENDAR components cannot contain more than 1 PRODID'

$ vdirsyncer -v DEBUG sync | sed 's,\\r\\n,\r,g'
...
debug: b'BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//K Desktop Environment//NONSGML libkcal 4.3//EN
X-KDE-ICAL-IMPLEMENTATION-VERSION:1.0
PRODID:DAVx5/4.4.1-ose ical4j/3.2.19
 (com.simplemobiletools.calendar.pro)
PRODID:-//PIMUTILS.ORG//NONSGML khal / icalendar //EN
PRODID:DAVx5/4.2.3.4-ose ical4j/3.2.5
PRODID:DAVx5/4.0-ose ical4j/3.1.0 (com.simplemobiletools.calendar.pro)
PRODID:DAVx5/4.4.4-ose ical4j/3.2.19
PRODID:+//IDN bitfire.at//ical4android (at.techbee.jtx)
BEGIN:VEVENT

The 'singlefile'-storage in col1.ics collects several PRODID: lines in the header.

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//K Desktop Environment//NONSGML libkcal 4.3//EN
X-KDE-ICAL-IMPLEMENTATION-VERSION:1.0
PRODID:DAVx5/4.4.1-ose ical4j/3.2.19
 (com.simplemobiletools.calendar.pro)
PRODID:-//PIMUTILS.ORG//NONSGML khal / icalendar //EN
PRODID:DAVx5/4.2.3.4-ose ical4j/3.2.5
PRODID:DAVx5/4.0-ose ical4j/3.1.0 (com.simplemobiletools.calendar.pro)
PRODID:DAVx5/4.4.4-ose ical4j/3.2.19
PRODID:+//IDN bitfire.at//ical4android (at.techbee.jtx)

...

[chr-x]

my config:

[pair col1]
a = "col1_local"
b = "col1_remote"
collections = null

[storage col1_local]
type = "singlefile"
path = "~/caldav/vdirsyncer/col1.ics"

[storage col1_remote]
type = "caldav"
url = "https://webdav.at.home:5232/chr/col1/"
username = "myname"
password = "mypass"