Calendar: Appointments "All day"

[a8907433]

I read many posts during the last years about double appointments in Google/EPIM calendar, but I didn´t mind, because I didn´t use ist, only the local calendar. But now....
I now use the calendar in mailbox.org. or at least, I try to. I use my calendar in EPIM for daily notes, stored as appointments in calendar. This works fine- in EPIM. But when I export and then try to import the ical into mailbox.org calendar, I get ID collissions, many appointments with the same ID.
So looked into the appointments what could cause this... I found, almost all of them haver set "all day event". In EPIM this seems to be no problem at all. So how could I get an ics file which causes no collisions?
I tried agenda view to remove all "all days" with one click, but there is no column with "all day".

I forgott to mention: I tried to import single categories, but that causes double entries, tripple entries and so on....

Edit: How could I make my EPIM-calendar "standard", so that the resulting .ics would cause not collisions, multiple entries?

Single edit appointments is impossible, there are thousands....

Edit: "all day" is not to blame. Now I export and import single categories. And still there is an ID collision.... In this category it is easy: I simple copied an appointment and pasted it. So, its easy to solve...... just change 200 entries...
As a suggestion I have: Please make copy & paste create a new ID, so that there in case of ical ex/import there is no collision!

Edit: Now I tried many exports/imports of ical´s. Changed something in copy/paste entries. No success.

2 remarks: 1) Workig in calendar produced some errors in EPIM. I would send the error message, IF THE PORTABLE VERSION WOULD ITSELF RECOGNIZE AS MAILPROGRAM!!! But this works via Windows-call-mailprogram..... wouldn´t work, if there is no mailprogram installed because it is portable...

2) Now tried another approach: I exported all appointments and imported it in another extern calendar (https://kalender.digital)- this worked. From there I export all appointments and reimport it into mailbox.org...... and this works!! So expoting/importing it to https://kalender.digital removes the bugs in the .ics, because exporting from there and importing it to mailbox.or works!

This is not a cheap solution, but it works.

Last Edit: It removes not all double entries, but at least it produces no error on import

[admin]

EPIM adheres to the iCalendar standard when exporting data into this format. Therefore, the issue you are experiencing may be related to the service into which you were attempting to import the exported data. If you need help troubleshooting this further or have specific questions, feel free to ask!