The company recently upgraded to Exchange 2007. Since the upgrade users who are still on Outlook 2003 (SP3) get the following error for some meeting requests:

You cannot respond to a meeting without an organizer. You must add an Organizer field to the item.

The item has an organizer field filled in.

  • Exchange is 2007 with SP1
  • MS Office (incl Outlook) is 2003 with SP3
  • Some users are using iPhones to accept / reject meetings. The iPhones never get an error like this.
  • There are no delegates for the user attempting to accept or reject the meeting.
  • Sometimes the meeting was previously accepted, sometimes not. We have not detected a pattern in the meeting requests that trigger the issue.

I've found a few people asking the same question on other websites but no answers. Experts Exchange claims to have an answer but from looking at the discussion at the bottom of the page I'm pretty sure they don't.

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    Haven't seen this, so just a guess.. but has there been any inconsistency with the x500 addresses (legacyExchangeDN property in active directory) with the organizers of the broken meetings? Outlook may be seeing one x500 address that comes in on the message, but trying to respond to an old x500 address that it has cached in the NK2 file. (The correlary "wild guess" test would be to have some users having the issue blow away their NK2 file) – Shane Madden Mar 7 '11 at 2:31
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    I agree with @ShaneMadden - check that all mailbox objects (users) have correct mail aliases attached. Does this happen with newly connected Outlook 2003 clients or only existing ones? – Ashley Steel Oct 2 '11 at 10:00

The latest KB that I have found at Microsoft is from October 9, 2011. As you can see at the below website, the exact error message you described is listed. Please remember this is a "possible" fix... not guranteed to solve your problem.


One of the biggest issues that cause what you are facing is the fact you probably have computers that are using Microsoft Outlook 2003 that have not been updated since BEFORE Outlook '07 has come out. This would cause an error due to the older software not knowing how to communicate to '07. The best possible solution is to have all your computers updated with the latest Microsoft updates. I know in some environments this isn't always possible due to the fact an update has the potential of not being supported by certain software you are running in your environment...

Suggestion: Obtain a machine that you see has this problem. Make sure this is not a priority machine, where if the hotfix causes a problem will adversly effect anything. I suggest having all the latest windows updates period, especially the service packs but doing 1 at a time can better help troubleshoot the issues and cause less impact to the company.


I'd verify the file versions found in this kb article (I realize it is pre-SP3):


I would suspect that one or more of these files are out of date, perhaps through a third party program or unsuccessful updates.

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