Ical data was modified

I see those errors in LOG. Can someone tell me what has been modified? Maybe I can change something in my Apple Calendar to prevent those messages?

Im using the CalDav integration.

2023-02-04 12:51:40.840 ERROR (SyncWorker_2) [root] Ical data was modified to avoid compatibility issues
NoneType: None
2023-02-04 12:51:40.842 ERROR (SyncWorker_2) [root] ---
+++
@@ -5,7 +5,6 @@
BEGIN:VEVENT
DTSTAMP:20230204T115140Z
CREATED:20191109T203705Z
-DTSTAMP:20230116T154244Z
LAST-MODIFIED:20230116T154244Z
LOCATION:Amsterdam Zuid Station\nAmsterdam\, Netherlands
RELATED-TO;RELTYPE=X-CALENDARSERVER-RECURRENCE-SET:1EE2E221-744B-4B78-AAB

Hi, don’t know the answer to your problem but have you updated your HA since, and if so: did you look at the release notes & breaking changes?

Updates to:

Home Assistant 2023.2.1
Supervisor 2023.01.1
Operating System 9.5
Frontend 20230202.0 - latest

No breaking issue about Calendar.

I see also that Caldav not allow “All Day” and I use it for a very long time without issues.
Now added 2 new calendars with also “All Day” events and they now showing up anymore…

But did you install a new HA release which has caused this issue?
If so, what was the previous version and check from there on the release notes.

On my test HA I also see all those errors when a CalDav event is a “All Day” event.

There is nothing. I always read the breaking issues before upgrade. So I know what to change.

The not possible “All Day” on caldav sounds strange, because there are lot of things that has to be all day. And now its not showing it

Sorry man, can’t help you…

Calendar shows off but the all day event is in an attribute.
The correction maybe something with how HA local calendar works.

A all day event is from 04-02-2023 until 05-02-2023 (so when it become 05-02-2023 the event ends)
In Caldav its from 04-02-2023 until 04-02-2023 (so just for that day)

Otherwise I can’t explain the corrects also

@poudenes having similar issues over here. Did you make any progress on this topic? Although, here it is not an “All Day” event…

Seems like the root of the issue was found (and it is harmless), see:

No progress. I ignored the errors. And saw the issue also. Let’s hope they will fix it.

Is this back with the September 2023 release? Or is it just me?

Yes, I am seeing this error as well in the logfiles:

Logger: root
Source: /usr/local/lib/python3.11/site-packages/caldav/lib/vcal.py:107
First occurred: 11:37:24 AM (2 occurrences)
Last logged: 11:52:25 AM

Ical data was modified to avoid compatibility issues (Your calendar server breaks the icalendar standard) This is probably harmless, particularly if not editing events or tasks (error count: 1 - this error is ratelimited)
Ical data was modified to avoid compatibility issues (Your calendar server breaks the icalendar standard) This is probably harmless, particularly if not editing events or tasks (error count: 2 - this error is ratelimited)
NoneType: None

what would be the right way forward to solve this? The above issue is closed? Is this core related? do you guys know if an issue is already logged?