I kept getting this in the event logs…

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.
– Default Offline Address List

And various event sources pointed me to a registry key..

Event ID 9340 Source MSExchangeSA:
Event ID 9360 Source MSExchangeSA:
Error message when a user performs the Send/Receive operation in Outlook:”Unknown error 0x8004011B”:

Now my error didn’t quite sound like Philip’s in:
MPECS Inc. Blog: SBS 2003 to 2008 Migration – Exchange OAB 9331 and 9335 Along with Outlook 0x8004010F Errors:

So I’m going to do this registy thingy.. and see what happens and report back in a day or two.

  1. Click Start, click Run, type regedit in the Open box, and then click OK.
  2. Locate and then right-click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters
  3. Point to New, and then click DWORD Value.
  4. Type OAL post full if diff fails to name the new value.
  5. Right-click OAL post full if diff fails, and then click Modify.
  6. In the Value data box, type 1, and then click OK.
  7. Exit Registry Editor.
  8. Dismount and then mount the Public Folder Store again



One Response to OALGen encountered an error while generating the changes.oab file for version 2 and 3

  1. Kyle Heath says:

    I had this issue and found the email virus scanner was set to block the attachment extension .OAB The offline address book is downloaded using at attachment with this extension so this change, that had been made by the customer, caused the issue. Worth checking just in case someone else has made a change!