Bug in EWS: Invalid iCal format if recurrent event modified RRS feed

  • General discussion

  • Hi,

    I have found a Bug in the Exchange EWS interface. I hope by writing it here it reaches the right MS Developers. Otherwise please let me know how I can report the bug on a better way.

    Used Exchange Version: 15.1.396.33 (Exchange 2016 CU1)


    Create a recurring event and modify one instance of this event series. Now if you query the calendar item through EWS, Exchange 2016 creates an invalid iCalendar data in the MimeContent field. I.e., it has a "BEGIN:VCALENDAR", but the "END:VCALENDAR" is missing.

    How to reproduce it:

    1. Create a recurring event with no end date. E.g. every Monday at 10am on OWA/Outlook Online (I used as start date 29th of August 2016)
    2. Query the calendar item through EWS and check the MimeContent field. It's OK, it contains a END:VCALENDAR
    3. Change a single instance by moving it to Tuesday 10am (in OWA), I moved the one from 19th September to 20st September 2016
    4. Now query the recurrent calendar item again and voilà: the "END:VCALENDAR" is now missing


    I tested it on Exchange 2010 and there it worked as it should. This problem only occurs on Exchange 2016.

    First I thought it's a problem in Gnome Evolution Mailer, so here's the original bug report for Gnome: Gnome EWS Bug

    Here are the Queried Calendar Items on Exchange 2010 (I decoded the base64 encoded MimeContent):

    These are all fine and as you can see on Ex2010 it inserts the END:VCALENDAR

    On Exchange 2016:

    On the modified sequence CalendarItem you can see that the END:VCALENDAR is missing.

    If you delete the modified instance, then it is again correct.

    Hope this helps to solve the bug!

    Wednesday, September 14, 2016 8:46 AM

All replies

  • This bug was also found by others, eg. the DavMail team:



    Wednesday, September 14, 2016 9:15 AM