Received 2 appointments, same date, same content, just different hours. Since then I receive message from iCal: Access to “Subject” in account “iCloud” is not permitted. The server responded "403" to CalDAVWriteEntityQueueableOperation. It's a bug!

The problem seems to esacalte, because changed inviations seems not to be accepted. I received today a changed appointment from a partner, whoe definitely use MS Exchange. Opening the .ics file in his Mail I receive the same error message, whereat the changed appointment was stored in my local calendar.

Having a look in the console messages:

4/25/13 8:32:14.494 AM CalendarAgent[176]: [com.apple.calendar.store.log.caldav.queue] [Operation [<CalDAVWriteEntityQueueableOperation: 0x7fd1ee2060d0; Sequence: 655>] was forbidden, server reason: [[<CoreDAVErrorItem: 0x7fd1ef319760>]: DAV:error]

<?xml version="1.0" encoding="UTF-8"?>

<A:error xmlns:A="DAV:">

<B:valid-attendee-change xmlns:B="urn:ietf:params:xml:ns:caldav"/>

<F:error-description xmlns:F="urn:mobileme:davservices">Attendees are not allowed to overwrite one type with another. calendar / schedule</F:error-description>

</A:error>

]

The previous invitation I had linked to same calendar, the changed invitation is now locally saved.

In the past I never had those problems and now for every changed appointment, driven by several services I always face the same error message.

The console message doesn't reflect the correct status, because of the remark according the attendees. The same person who send me the previous invitation send me also the chaneged invitation.

Definitely, it's a problem with iCloud.

I have deleted all invitations which create problems and read them again in a local calendar, which is just on my mac.

I can read then all those time-changed invitations without any problems. No error messages anymore! No warnings and no errors in the console.

Wherefor I need iCloud?

Tried on another mac with same result. I don't think ist my mac.

When internet connection is off, or invitations are normally stored on my local calendars, it doesn't seem to me this is caused by a local problem. So far I'm local no problems. Just in the moment calendar synchronize with iCloud the problems occur.

Oh no, don't misunderstand me. I want to investigate further.

What do you suggest I should do next?

This morning I did that. My daughters macbook needed to be reinstalled and I still have an older macbook which I reinstalled in parallel. I leave my iCloud account on this macbook inactive and I could read all invitations, without any error messages.

As next I read all invitations which cause me problems in a new local calendar on my actual macbook. Everything was fine. The time-changed invitations could be read, without any problems. My partner called me and asked me what's wrong, because he always receive declined and agreed invittations. (I have deleted and reread the invitations)

As next I put the invitations again in iCloud and the error messages didn't hesitate to arise periodically.

Correct

It took some time ...

I had activated iCloud on this older macbook, which have actual Lion release installed. (It's to slow for higher releases)

1. The local calendar disappeared (?)

2. The synchronize took a long time.

3. I reread the last invitations and my local calendar appear again. The problematic invitations are still in the lcoal calendar and don't cause any problems.

Until now, no problems.

I suppose you want I should transfer as next the invitation from the local calnedar to an iCloud calendar?

I'm on the same old macbook, freshley installed.

o.k. I have to correct my last words. The "Test-calendar" was in iCloud. I have a lot of them, as you mentioned this could be an error. It's not, the calendar was moving to iCloud.

Copying the invitation doesn't cause any problems. But I suppose this is because this was already the changed, the last stauts, so to speak and the app just copy the entry to another calendar.

Being on the same macbook (the old on and freshley installed), I deleted now the invitation from iCloud calendar and read again the original invitation. Everything was fine. I read as next the time-changed invitation in the iCloud calendar and the error message appear again. Lion differ in the error message, doesn't offer "Ignore" "Try again" and "Revert to Server". Offer just "Go offline" or "Revert to Server".