Hi, My OAL updates have been failing with the following errors below. They stopped occurring at one point and restarted with a Legacy DN specified which I can't locate in AD. Exchange 2007 SP 2 Event log errors every scheduled update of the OAL: Event ID 9360 Source MSExchangeSA OALGen encountered an error while generating the changes.oab file for version 2 and 3 differential downloads of address list '\Global Address List'. The offline address list has not been updated so clients will not be able to download the current set of changes. Check other logged events to find the cause of this error. If the cause of the problem was intentional or cannot be resolved, OALGen can be forced to post a full offline address list by creating the DWORD registry key 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters\OAL post full if diff fails' and setting it to 1 on this server. When OALGen next generates the offline address list, clients will perform a full OAB download. After that time, the registry key should be removed to prevent further full downloads. Also, Event ID 9340 Source MSExchangeSA A new parent Legacy Exchange DN container value '/o=NT5/ou=<alphanumeric number removed>' was found during generation of the differential update file for offline address list '\Global Address List'. This will force clients using this offline address list to do a full download of the offline address list.

Please read this article for steps on how to troubleshoot and identify that account: http://technet.microsoft.com/en-us/library/bb219051(EXCHG.65).aspx How to Troubleshoot Parent Distinguished Name Changes http://blogs.msdn.com/dgoldman/archive/2005/11/18/OAB-PDN-Changes-and-Exchange-Site-Consolidations.aspx

Thanks for the help. What concerns me about the information is that they are not Exchange 2007 specific. For instance, the OABInteg tool does not apply to 2007 according to http://support.microsoft.com/default.aspx/kb/907792. Is there documentation that supports the use of this tool in Exchange 2007?

http://blogs.msdn.com/dgoldman/archive/2006/09/09/747992.aspx The latest version should with some caveats.

Thanks, I'm just missing the Outlook 2007 client on the Exchange server.

Hold on now. Did you set the registry setting for "OAL NT5 DN Rejection" yet? You dont necessarily have to run on the Exchange Server.

I haven't changed any registry setting yet. Can I run the OABInteg tool on a 2003 server with Outlook 2007? Thanks for your help.

I would set that registry setting first and see if it helps you identify the account. You should be able to run the tool from any workstation with Outlook on it.

Just to be clear, OAL NT5 DN Rejection was provided as a hotfix in exchange 2003 sp1 but builtin to sp2 and exchange 2007? this reg edit should go in the registry of all servers with the mailbox roles? Thanks

Just on the server that generates the OAB. And yes, it should work for 2007.

Hi, Please first change the registry to check this issue: Installing Exchange 2007 or 2010 in to a mixed organization will create a valid PDN entry and break OAB Generation http://blogs.msdn.com/dgoldman/archive/2007/08/10/installing-exchange-2007-in-to-a-mixed-organization-will-create-a-valid-pdn-entry-and-break-oab-generation.aspx If the suggestion is not working, you can use the OAB tool to find the problematic LegacyExchangeDN. Thanks Allen

Thanks for the help but I'm confused. Are you referring to the "OAL NT5 DN Rejection" reg edit or this one from the link you provided: 1. Turn up logging: http://blogs.msdn.com/dgoldman/archive/2006/08/26/725860.aspx 2. Build your Offline Address Book. 3. Look for the 9340 and 9360 event id for the following legacyExchangeDN ' ' 4. open up Regedit 5. Navigate to the following registry key 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters\ 6. Add a new DWORD Value 'OAL Post Full If Diff fails' 7. Set the value to 1 8. Rebuild your Offline Address Book and look for the 9107 event. Make sure you did not get a 9340 and 9360 event 9. Remove the registry key and you are done! 10. Turn down logging: http://blogs.msdn.com/dgoldman/archive/2006/08/26/725860.aspx

THe 'OAL Post Full If Diff fails' key will force the OAB to post the full. The OAL NT5 DN Rejection key may help you in indentifying the user. Most likely its someone who is associated with invalid Address List, or whose mailbox was correctly disconnected, etc...

Thanks, I will enable OAL NT5 DN Rejection. Do you recommend keeping this parameter or just using it to find the object with the missing DN?

I dont think it hurts you to leave it.

Perform the following procedure to edit the registry. On the Exchange server, start Regedit.exe. Open the following registry key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeSA\Parameters Right-click Parameters, point to New, and then click DWORD Value. For the new value name, type OAL post full if diff fails. Double-click OAL post full if diff fails. In Value data, type 1. Click OK. Close Regedit.exe. for details got through : http://www.microsoft.com/technet/support/ee/transform.aspx?ProdName=Exchange&ProdVer=8.0&EvtID=9360&EvtSrc=MSExchangeSA&LCID=1033

OAL NT5 DN Rejection is what is needed because the PDN is bogus. If the a new PDN existed, OAL post full if diff fails would be required before the partial updates can occurr. Thanks AndyD and all contributors for your time.