Fixing Outlook indexing problems

More than a few people have problems with the Outlook ‘instant’ search feature.  It’s great when it works but too often you get the dreaded “Search results may be incomplete because items are still being indexed”.

Sometimes all you need to do is wait until indexing is complete.  Depending on the size of your hard drive and Outlook data, that can take many hours.  Sometimes you might need to leave the computer on overnight so the indexing service can catch up.

But too often, the indexing never ends.  Outlook always shows the ‘incomplete index’ error message above no matter how long you wait.

There’s many possible sources of the problem and therefore solutions.  Here we’ll try to explain what’s happening, what Microsoft recommends and what might actually work.

Don’t blame Outlook

Usually, Outlook is to blame for a problem but not this time.  Outlook’s search relies on the Windows to find items.  You need to look at the Windows Search Service and get that working correctly.  Once that’s done Outlook should be able to search itself quickly.

Windows Search is the current name for the indexing service.  It was once called Windows Indexing Service or Windows Desktop Search.  Whatever it’s called, the software sits in the background and creates an index of all the files and Outlook items.  This index (like the index in a book) lets you find things much faster than scanning each file during individual searches.

Blame Windows Indexing

The trick to getting Outlook search working is to repair the Windows Search (WS).  This is the part of Windows which indexes the content of all the documents, images and other files on your computer, plus Outlook data, so that it can be searched quickly.

Now for the bad news.  The Windows Search sucks.   It’s a core piece of Windows which was revamped some years ago, given the usual name change and now appears to have been ignored.  “Near enough is good enough’ seems to be the Microsoft motto.   We’ve complained for years about the Indexing service, for example the lack of an easy ‘Index Now’ option to speed up initial indexing.

When the Search Service works, fine, no problem.   But it’s not very robust and too many little things can make it fall over.  The error handling is awful so tracking down the problem is too ‘hit and miss’ for anyone’s liking.

Microsoft loves to blame third party programs for indexing troubles but the hard fact is that indexing should not fail so easily.   And Microsoft’s excuses don’t make much sense when one of the possible problems is Hyper-V, another part of Windows!

Microsoft’s solution

Microsoft’s main recommendations are in this Knowledge Base article.  It covers the basics of Indexing in Outlook plus some details of Outlook specific indexing errors.

However the indexing problem that’s showing up in Outlook might not be caused by an Outlook problem.  As we’ll see below, there are other non-Outlook issues that can stop indexing of your mail store.

Other solutions

Once you’ve tried the official Microsoft route, you have to look at other possibilities.  Here it gets tricky because you have to just try things and hope it might work.

Here’s one fix that we’ve heard about and prompted us to write this article.  It came from a determined Office user who hammered at Microsoft Support until they came up with an answer.  The solution is quite amazing in several ways …

Indexing and Hyper-V

It was a Lenovo laptop, quite normal in all respects but the indexing refused to complete.  Months of trial and error plus countless emails to Microsoft Support before they recommended disabling Hyper-V.

Hyper-V is the virtual machine service that comes with high end versions of Windows.  Normally it’s available but not installed because most people don’t need it.  If you want Hyper-V, it’s simple to install from Control Panel | Programs then add a Windows feature.

For some reason, according to Microsoft, Hyper-V is installed and activated on these Lenovo laptops.  That should not be a problem, plenty of people use Hyper-V.  Windows Search should work with Hyper-V.  After all, they are both Microsoft-made and part of Windows so you’d expect them to play nice.

Apparently not always.  Microsoft Support recommended to our informant to stop the Hyper-V service and disable it.  And it worked!  The months of indexing hassles stopped, Outlook was fully indexed and could search properly.

Why?  How?  MS Support didn’t explain.   It worked so everyone was relieved.  But it’s just one example of how flaky Windows Search Service can be.

Error Handling

To see a little of what’s happening with Windows Search, go to Control Panel | Administrative Tools | Event Viewer.  Under Event Viewer (Local) | go to Windows Logs | Applications.   You’ll get a long list of events, too long to deal with.  To get a relevant and manageable list, choose Filter Current Log then pull-down the Event sources list.  Choose Search and Search Core from the list then choose OK.

Now you can see only the Search relevant events.

Tip:  you’ll probably keep returning to this filtered list as you try to figure out your problem.  From the bottom of Actions list (on right), choose Save Filter to Custom View.  Now your filtered list will appear with a single click to the Custom View list on left.

Under that view you’ll see all the relevant Windows Search events, information, warnings and errors.

Information entries  usually tell you when the Search service started or stopped.

Warnings are non-critical problems.  A typical Warning looks like this:

Crawl could not be completed on content source <  something >.

Context:  Application, SystemIndex Catalog


       (HRESULT : 0x80004005) (0x80004005)

According to MS Support, this warning with the 0x80004005 code can be ignored.

Error.  If you see a lot of these errors then the indexing is having a problem.

Log Name:      Application
Source:        Microsoft-Windows-Search
Event ID:      7042
Task Category: Search service
Level:         Error
Keywords:      Classic
The Windows Search Service is being stopped because there is a problem with the indexer: The catalog is corrupt.
     The content index catalog is corrupt.   0xc0041801 (0xc0041801)

Ideally that error should be followed by this error event:

The search service has detected corrupted data files in the index {id=4810 - enduser\mssearch2 \search\ytrip\tripoli\ inverted\decodinglayerpages.h (423)}. The service will attempt to automatically correct this problem by rebuilding the index.


       The data is invalid.   0x8007000d (0x8007000d)

Which means that the index is being recreated.

A corrupt index being deleted and recreated seems to happen occasionally.  We found the above errors on one of our machines without knowing it had happened a few months ago. It’s a pity the Event log doesn’t show when the index is up-to-date and has paused until new or changed files are detected.

The problem comes when Windows Search never stops indexing or the index is continually corrupted, deleted and recreated in a never-ending cycle.   There’s often no information on why the index was corrupted.

Other possibilities

We’ve looked around and here’s some other things you might try to make Windows Search play nice.

Search the web for the exact error code used in the event viewer.  Other people in the same situation might give you some clues.

Move the index off a solid state hard drive.  Putting the index on an SSD would seem ideal but it seems some caching on these drives can confuse WIS.  Relocate the index to a standard drive instead.

Look for third party caching or drive performance tools.  Again, these bits of add-on software should not hurt WIS, but disabling them seems to help indexing return to normal.

Try removing some folders or Outlook stores from the indexed content.  It’s possible that something in the files or Outlook data is giving the Indexing Service a nervous breakdown.

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