In Part 1 of this series we have already discussed the evolution of NK2 to AutoSuggest and then to Auto Complete streaming files. If you haven’t read it, I would recommend reading that, As the terminology used in this article would make more sense then. Anyways, As I mentioned in Part 1 that An user complained that the autocomplete history of her Outlook 2013 get washed off every now and then. i.e. it last not more than two days, as always my first assumption was that the user is confused 🙂 but when I checkout her PC and had a look at the autocomplete streaming files, I had to agree to the user, check out the image below.

Image of multiple streaming files

Notice the numerous autocomplete streaming files created for a single outlook profile

Notice the numerous autocomplete streaming files created for a single outlook profile

The numerous autocomplete files makes it evident that AutoComplete files is getting changed/replaced repeatedly hence the user is loosing her outlook autocomplete information.

So to troubleshoot this issue we followed multiple steps and while researching around we did found a lot of useful information about how to troubleshoot AutoComplete issues.  If you do not have much Idea about what is a  Outlook AutoComplete file or NK2 file then you should definitely read the Part 1 of this article series to clear those concepts before reading this. This article is a collection of steps which can be performed to troubleshoot Autocomplete issues.

Troubleshooting Steps

SafeMode for Outlook

Many would feel that this step is irrelevant here but This should be the first step for any outlook issue troubleshooting, Many issues with outlook happen because of some third-party plugin.  So it is always advisable to see if the issue persist in safemode of outlook and if not than probably just disabling the third-party plugin with do the task.

How to open outlook in safe mode ?

  • Hold Ctrl key as you click the Outlook shortcut.
  • Vista or Windows 7 user can type outlook.exe /safe in the Start Search field on the Start menu then press Enter.
  • Windows 8 user can press Windows key to get the  Start screen, then type outlook.exe /safe.
  • Hold the Windows key and press R, then type outlook.exe /safe in the Open field and click OK.
  • For a more permanent solution open the properties of Outlook Shortcut and add /safe to the end of of shortcut path.

About How to Disable plugin, Please refer our other article about Evernote Plugin causing issue and checkout the steps which we took to disable the plugins.

Ensure Auto Complete feature is enabled

This section details how to enable or disable the AutoComplete feature.

Outlook 2010 and Outlook 2013

To access the AutoComplete setting, follow these steps:

  1. On the File menu, click Options.
  2. Select the Mail tab.
  3. Scroll approximately halfway down until you see Send messages. Make sure that the Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines box is checked.


Outlook 2003 and Outlook 2007

To access the AutoComplete settings, follow the steps:

  1. Click Tools, and then click Options.
  2. Click the E-mail options button.
  3. Click the Advanced E-mail Options button.
  4. Make sure that the Suggest names while completing To, Cc, and Bcc fields box is checked. (The screen shot for this step follows.)

    The screen shot for this step.

Empty the Autocomplete Cache

In some instances, to get this working again in Outlook 2010, you may have to clear out the Autocomplete cache. If everything is gone already, then this won’t matter, but it should help with the problem of the cache resetting over and over

To empty the cache, go to File and click on Options. Then click on Mail and scroll down to the SendMail section.

send mail outlook

Click on the Empty Auto-Complete List button. It’s also a good idea to uncheck the Use Auto-Complete List to suggest names when typing in the To, CC, and Bcc lines box. Exit out of Outlook and then re-check the box. Try typing in a few email addresses and then exiting Outlook and opening it again and seeing if the names are still there.

You can also use the /cleanautocompletecache switch to clear the cache.

Close Outlook. Press Windows key + R to open the Run command and type or paste the following line and press enter to start Outlook.

outlook.exe /cleanautocompletecache

Rename/Delete the RoamCache folder

You can also completely get rid of your current cache and start from scratch, which might be the only way to get the problem to go away. You simply have to rename the RoamCache folder to something else and Outlook will create a new one when you start-up the program again.

For Windows Vista & 7:


For Windows 2000 & XP:

C:\Documents and Settings\Username\Local Settings\Application Data\Microsoft\Outlook\RoamCache

If the users are losing addresses of people they recently replied to (but not older addresses), it’s because Outlook crashes or does not close properly and the changes are not written to the NK2 file. The existing *.NK2 shouldn’t be replaced by a clean *.NK2 if this happens, but new addresses you’ve sent new mail to or replied to won’t be saved to the file. Less used addresses are replaced by new addresses when the NK2 contains 1000 addresses in Outlook 2003 or 2000 address if using Outlook 2007.

If all addresses disappear, it means something is corrupt and Outlook is replacing the NK2 with a new, clean one.

Autocomplete List Cache Size

There is a limit of 1000 names on the autocomplete cache in Outlook. The limit can be raised in Outlook by use of a registry setting. Note: this value will not exist by default and is only needed if you want to change the limit.

Outlook 2010: 


Outlook 2007:

Outlook 2003:

Outlook 2002:

DWORD: MaxNicknames
Value: Between 1 and 2000, in decimal

Replace Autocomplete streaming file

Another valuable step would be to copy a working Autocomplete file from another PC and past it in problem RoamCache folder and then rename it as the current autocomplete file.

Hope this Article helps you to fix the issue in hand, remember you can reach out to us  for paid support options, here

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An automobile enthusiast at heart and computer geek by profession, started my Career with MS in 2005.Left Jobs and started Pledge Technologies (the parent company to Grishbi) back in 2009.We have been providing IT consulting to various Small and Medium businesses across US and UK since then.Our company specialises in Microsoft Server technologies like AD, Exchange, the rest and with numerous Office 365 migrations under our belt, we quite an expert with that too. Whatever we learn in our day to day life, we share it back on Grishbi as a Thank for all the love and support our customers have given us.
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