Occasionally during mailbox migrations or via normal client-side troubleshooting, a user’s Outlook client will lose the type ahead cache (autocomplete).  While there have been different variations of this problem over the years and over the different versions of Outlook, the result is the same for the user:  Panic!

Make no mistake, in some cases, there’s nothing that can be done, and the user will be forced to rebuild this cache organically.  However, before delivering this bad news, it’s worth trying the steps below.

To be clear, we are talking about this:

  1. Close any instances of Outlook that might be open on the client PC.
  2. Navigate to the C:\Users\UserName\AppData\Local\Microsoft\Outlook\RoamCache\ directory.
  3. There may be a lot of files in this directory but we are looking for the most recent file that has a name starting with ‘Stream_Autocomplete_’ and is more than a couple KB in size.
  4. When you have found the file, right click on it and choose ‘Copy’.
  5. Then right click the ‘RoamCache’ folder and choose ‘Paste’.
    1. Note: This is extremely important since it’s very easy for this file to get overwritten in the upcoming steps.
  6. There should now be 2 copies of the file.
  7. Now, find the most recent file that has a name starting with ‘Stream_Autocomplete_’.
    1. This file will likely be very small (a couple of KB).
  8. Copy the name of the file to a blank Notepad.
  9. Delete this file.
    1. The one that is small and most recently modified.
  10. Find the copy of the file that you made earlier, right click on it, and rename it to the file name you put in Notepad.
  11. Start Outlook.
  12. Click ‘New Email’ and start to type in names that you are expecting to find in ‘Autocomplete’.
  13. You should see them again.
  14. If this did not work, which is common, close Outlook and repeat the process starting at step 2.
    1. Usually if the first time through doesn’t work, the second time it inexplicably will.

The Outlook cache may seem like a minor thing, but people come to rely its convenience.  It’s kind of like how nobody remembers phone numbers anymore because they are all in our phones.  Losing autocomplete can cripple a user’s productivity and be tremendously frustrating.  Fixing this problem for someone is a quick way to earn ‘Hero’ status with them.