We are an Exchange 2013/ Outlook 2013 shop.  The majority of clients are running Outlook in Cached Mode.  Recently, users have been reporting that their AutoComplete isn't working properly when attempting to address a message.  It was our understanding that the location of the AutoComplete list was moved from the locally stored .nk2 file to the user's mailbox.  Outlook then copies this information to a "RoamCache" folder.

Can anyone provide insight on why this may get corrupted?

I wrote up the following troubleshooting guide and wanted to ask if anyone can make any suggestions or if there was anything else that can be added.

1.  Within Outlook, ensure the Use Auto-Complete List checkbox is enabled in File, Options, Mail, Send Messages.
2. If the Auto-Complete List checkbox is already enabled, try this:
   • Open Outlook Web Access (OWA)
   • Have the user login.
   • Have the user attempt to address a message.  The list is saved in the users mailbox, so the user should be able to access the same list using OWA.
3. If the problem only appears to be in Outlook, try this:
   • Close Outlook.
   • In Outlook, switch from cached mode to online mode.
   • Open %localappdata%\Microsoft\Outlook
   • Right-click the RoamCache folder and rename to old_RoamCache.
   • Switch Outlook back to Cache mode.
   • Reopen Outlook.  When Outlook reopens, the list should be pushed back down from the mailbox to the cached folder on the users workstation.
4. If both exists in both Outlook and OWA, use the Empty Auto-Complete List option that is in Outlook options.

Hi,

It's hard to tell what exactly caused it corrupted, but your troubleshooting guide is quite professional in my opinion.

Have you installed any new program recently? Or something that may work with Outlook? As the AutoComplete information is stored in the mailbox, as far as I can tell, possibly it would be corrupted by some programs that need access to the local data file(.ost). Try the Scanpst.exe tool to scan and fix the issue found in the .ost file if the issue occurs the next time.

Regards,

Melon Chen
TechNet Community Su

Hi, Melon.

The information I found out was second hand.  I was eventually able to visit the user and found out she was having trouble with one specific address.  When I tried addressing a message, other addresses came up in Outlook as well as OWA.

I tried addressing the message with the missing/failing address.  Sent a test message so that it was successfully used once.  Closed and reopened Outlook.  When I attempted to address the message with the "missing" address, AutoComplete worked successfully.

With that being said, it appears this user may be affected by the limitation of 1000 entries in the AutoComplete list.  I'm going to suggest either deleting entries or consider expanding the number of entries from 1000 to 1500.

Info about the limitation of AutoComplete were found here: 

I'm a little reluctant about the second option.

Hi,

How is this going now?

To confirm if you have reached the limit, remove one you don't need, then try the one which was missing, check the result.

Regards,

Melon Chen
TechNet Community Su