Hi, I realise this has been answered in some length else where on the Exchange forums, however none of the answers seem to fix this error for me. Basically - we had a 2003 to 2010 mixed environment and everything was working. Whilst i was away for the birth of my child, my manager decided to remove our 2003 server and format it, thinking it was no longer needed as all mailboxes are now on 2010... Since this everything works other than the OAB. I create a new user and they appear in the address book if we dont have cached mode enabled on our clients and if we log in to OWA they appear, however when we try to download the OAB we get this error. I have checked that our Default Offline Address Book has web based distribution and public folder distribution enabled and is assigned correctly to the mailbox database. I have also restarted the relivent services etc and given it just under 24 hours to replicate etc, but we still appear to be getting this error. I have checked and i have the relivent LZX files appearing in both the OAB\SID location within ClientAccess and V14 location. Any thoughts at all before i phone MS support and get one of the specialists to take a look? Cheers, Rich

Can you check this http://support.microsoft.com/kb/951576 Do you need PF based distribution or not? i.e OLK 2003 clients still around?Sukh

Can you check this http://support.microsoft.com/kb/951576 Do you need PF based distribution or not? i.e OLK 2003 clients still around? Sukh Hi Sukh, Unfortunatly i have ensured this is correct as on the page and it still does not work. Rich

Hi Riso Did you try above suggestion? Cheers Zi FengZi Feng TechNet Community Support