As the title suggest, see below a snippet for a conversation from the trace for "FindConversation" against Office365.

As you can see, the ChangeKey is "CQAAAA==" for all the items (across conversations), and interesting enough, it is the same as in the documentation for FindConversation

https://msdn.microsoft.com/en-us/library/office/ff406144(v=exchg.150).aspx

Is this a known issue?

       <Conversation xmlns="http://schemas.microsoft.com/exchange/services/2006/types">
            <ConversationId Id="AAQkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgAQAB2NeP3GTQlDp5B7AWesrrw=" />
            <ConversationTopic>Kid's turning the dog green again</ConversationTopic>
            <UniqueRecipients>
              <String>John Smith</String>
            </UniqueRecipients>
            <GlobalUniqueRecipients>
              <String>John Smith</String>
            </GlobalUniqueRecipients>
            <UniqueSenders>
              <String>John Smith</String>
            </UniqueSenders>
            <GlobalUniqueSenders>
              <String>John Smith</String>
            </GlobalUniqueSenders>
            <LastDeliveryTime>2014-11-26T16:21:37Z</LastDeliveryTime>
            <GlobalLastDeliveryTime>2014-11-27T14:09:09Z</GlobalLastDeliveryTime>
            <HasAttachments>false</HasAttachments>
            <GlobalHasAttachments>false</GlobalHasAttachments>
            <MessageCount>1</MessageCount>
            <GlobalMessageCount>4</GlobalMessageCount>
            <UnreadCount>0</UnreadCount>
            <GlobalUnreadCount>0</GlobalUnreadCount>
            <Size>16099</Size>
            <GlobalSize>28992</GlobalSize>
            <ItemClasses>
              <ItemClass>IPM.Note</ItemClass>
            </ItemClasses>
            <GlobalItemClasses>
              <ItemClass>IPM.Note</ItemClass>
            </GlobalItemClasses>
            <Importance>Normal</Importance>
            <GlobalImportance>Normal</GlobalImportance>
            <ItemIds>
              <ItemId Id="AAMkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgBGAAAAAAC/m9YT3n+7RbfoU4MvIUlwBwDO121Po4OqQ7Wo59kdWfWgAAAAAAEMAADO121Po4OqQ7Wo59kdWfWgAAASN40cAAA=" ChangeKey="CQAAAA==" />
            </ItemIds>
            <GlobalItemIds>
              <ItemId Id="AAMkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgBGAAAAAAC/m9YT3n+7RbfoU4MvIUlwBwDO121Po4OqQ7Wo59kdWfWgAAAAAAEJAADO121Po4OqQ7Wo59kdWfWgAAANAp25AAA=" ChangeKey="CQAAAA==" />
              <ItemId Id="AAMkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgBGAAAAAAC/m9YT3n+7RbfoU4MvIUlwBwDO121Po4OqQ7Wo59kdWfWgAAAAAAEJAADO121Po4OqQ7Wo59kdWfWgAAANAp24AAA=" ChangeKey="CQAAAA==" />
              <ItemId Id="AAMkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgBGAAAAAAC/m9YT3n+7RbfoU4MvIUlwBwDO121Po4OqQ7Wo59kdWfWgAAAAAAEJAADO121Po4OqQ7Wo59kdWfWgAAANAp23AAA=" ChangeKey="CQAAAA==" />
              <ItemId Id="AAMkADMwZjkyMjExLTMzMGUtNGU5MS04OWIzLTAyY2ExYjM2ZjFiMgBGAAAAAAC/m9YT3n+7RbfoU4MvIUlwBwDO121Po4OqQ7Wo59kdWfWgAAAAAAEMAADO121Po4OqQ7Wo59kdWfWgAAASN40cAAA=" ChangeKey="CQAAAA==" />
            </GlobalItemIds>
            <LastModifiedTime>2014-12-05T19:12:48Z</LastModifiedTime>
            <InstanceKey>AQAAAAAAAQABAAAADQKSGAAAAAA=</InstanceKey>
            <HasIrm>false</HasIrm>
            <GlobalHasIrm>false</GlobalHasIrm>
          </Conversation>

• Edited by Erez Katz 21 hours 56 minutes ago

It looks like you get an abbreviated change key in the FindConversations results. If you do GetConversationItems, you get back the full key.

Abbreviated chang key should have different values for different items, since they are all the same, I am inclined to assume it is a bug in office365. I don't mind sticking with abbreviated change key, as long as they are consistent across calls. 

1) is this issue also present in non-office365 installations?

2) is there a way to force ews to give the full change key in FindConversations? GetConversationItems is limited to exchange 2013...

Thanks, 

 Erez