I'm running ARS 6.7 with Exchange 2010 SP2 RU 5 and have installed a test server with ARS 6.8. On the test box I have the Exchange management tools with service pack and the same updates as our servers.
It's fine with creating mailboxes and all that, I couldn't find any issues until I wanted to tweak the settings for room mailboxes. When changing settings on them it comes back with an error:
Administrive Policy returned an error.
Operation is not valid due to the current sate of the object
Operation is not valid due to the current sate of the object
Doing more testing, I realized that ARS 6.8 is actually not showing all the information for this mailbox. For example, the check box "Enable the Resource Booking Attendant" is unchecked on ARS 6.8 while for the same user it is checked in ARS 6.7. Looking into advanced properties, I see the value for that attribute edsva-msexch-enableresourcebookingattendant is just empty.
Then looking into the event log under Applications and Services Logs\MSExchange Management, it generates an error event everytime I just open the Resource Information tab of a user profile.
Event ID: 6
Source: MSExchange CmdletLogs
Part of the event text (text in blue replaced):
Get-CalendarProcessing
{Identity=USER-ACCOUNT-CANONICALNAME, DomainController=DC-FQDN} ARS-SERVICE-ACCOUNT-CANONICALNAME
Default Host-Local
2028
52
00:00:00.0625024
View Entire Forest: 'True',
System.InvalidOperationException: Operation is not valid due to the current state of the object.
at Microsoft.Exchange.Data.Storage.ExchangePrincipal.get_ServerFullyQualifiedDomainName()..
So everytime I go to that Resource Information Tab, ARS would shoot a Get-CalendarProcessing cmdlet to Exchange to get the necessary information and that fails. Maybe because it's not actually going to Exchange but trying "default host-local" instead, as it also complains about the Exchange server name. But as I said, other Exchange operations work just fine.
I've already re-installed the Exchange tools and triple checked they have the same version as the Exchange servers. And if you open the EMC on that ARS 6.8 test server, it works fine and manually running the Get-CalendarProcessing works as well.