You can receive the following error (0x80190194) in Outlook when trying to download a Web Distribution only enabled Offline Address Book. The error 0x80190194 is an HTTP 404 error:

C:\WINDOWS\system32>err 0x80190194
# for hex 0x80190194 / decimal -2145844844
BG_E_HTTP_ERROR_404 bitsmsg.h
# 1 matches found for "0x80190194"

The reason for this error message is that when an Outlook 2007 client downloads the OAB files they are not being found on the Client Access Server.

Here is the flow for downloading the OAB:

1. An Outlook client starts up.
2. The Outlook client talks to the autodiscover service and retrieves the autodiscover.xml file which contains the URLs for all of the Exchange Web Services.
3. The Outlook client parses this autodiscover.xml file and looks for the <EXCH> section which is for the internal corporate network, and <EXPR> for Outlook Anywhere (External).
4. You select Tools | Send/Receive | Download Address Book.
5. The Outlook client looks for the OABUrl which looks like this: <OABUrl>http://OABServer.domain.com/OAB/edb3e44f-c49b-4597-b996-cb1093405985/</OABUrl>.
6. Once the Outlook client locates the OABUrl the Outlook client makes a HTTPS connection to the OAB Web Virtual Directory specified in the <OABUrl>.
7. If the connection to the OAB Web Virtual Directory is successful the Outlook client  it will look in the directory for the OAB you are download and retrieve the OAB.xml file.
8. The Outlook client will examine the OAB.xml manifest file and find out what OAB files are needed for updating the Outlook client's local copy of the OAB.  

Now, the Default OAB Web Site on the Client Access Server will have a local directory associated with it that has the path of: <Drive Letter>:\Program Files\Microsoft\Exchange Server\ClientAccess\OAB. This is the location for the OAB files when they are copied over from the Mailbox server by the FDS (File Distribution Service).

If you are in a single server site these OAB files should be copied over immediately to this directory after the OAB has been generated. If you have a multi-server site where your  Client Access Server that is separate from your Mailbox server that is generating the OAB, the OAB files will be copied over under a few situations (not all are listed here):

1. A new OAB is created
2. A change to the OAB has happened
3. The OAB Generation Server has changed
4. The Default Polling Interval is up (this is 8 hrs by default).
5. There are new OAB files (new binpatch.oab file has been created).

One way to tell if your OAB files have been replicated to the Default OAB Web Site is to look for the event id 1008 in the application log. This event will be logged by the FDS (File Distribution Service) on the Client Access Server.

Event Type: Information
Event Source: MSExchangeFDS
Event Category: FileReplication
Event ID: 1008
Date: 11/28/2006
Time: 1:55:46 PM
User: N/A
Computer: OABServer
Description:
Process MSExchangeFDS.exe (PID=2484). Offline Address Book data synchronization task has completed successfully. OAB name: "Default Offline Address Book", Guid: edb3e44f-c49b-4597-b996-cb1093405985

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

If the OAB files are missing you will need to find out why the FDS service is not replicating them.

Workaround 1

Workaround 2 - This is just a workaround ONLY until you get the FDS replication fixed

1. You can go your mailbox server (OAB Generation Server) and go to one of the following locations:
• Local directory - C:\Program Files\Microsoft\Exchange Server\ExchangeOAB
• Unc path - \\ExchangeServerName\OAB\<GUID of OAB>
2. Copy the OAB directories that are needed for your clients over to the client access server location:
• c:\Program Files\Microsoft\Exchange Server\Client Access\OAB\

Once the files have been replicated to this directory the Outlook client will be able to download them and you will not receive this error.

Dave