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Troubleshoot the index keeps rebuilding and Understanding the Indexing Option, Indexing Status, and Searching Windows on Windows 10

We found this issue where the indexing keeps rebuilding every now and then. This caused the Outlook search to stop working as well as the Unread/Read tab.

Usually, the Event Viewer is a good start for pointing out the index/search issue. This time, however, we could not pinpoint the exact issue on this as the Event Viewer did not record anything!

The Environment

In our scenario, we have the following:

  • Microsoft Windows 10 Professional Version 21H2
  • Micorosoft Office Home and Business 2016 Version 2201 Build 16.0.14827,20028 32-bit
  • Has 3 Outlook Profiles: 1 Zimbra account, 1 Microsoft Exchange account with 2 archives mailboxes, and 1 Zimbra account with 8 archives mailboxes and 2 shared mailboxes.

The Finding

We found a couple of findings that might help to understand the issue. When we checked, the remaining disk space fluctuated between 2GB to 20 GB. We focus on removing unnecessary shared mailboxes that are not utilised. We did remove the shared mailbox which is a big one. This leads to the second finding below.

Need to redo rebuilding the index to get the number of items indexed recorded. We found the number which is around 170,270.

Under the Searching Windows on Settings, the indexing status has x number of indexed item and stay like that while the pending come up with randomly 20,000+ and go down to zero.

Every time the reindexing is completed, Outlook is not able to search after that for an unknown reason, however, the Windows search is still OK. When you do the Troubleshooter for Search and Index with Outlook search doesn’t return a result, it found the issue – Windows Search is not working and did the repairer as Administrator and it has fixed. And it runs again, it will the same thing – it found an issue – Windows Search is not working (loop)

We did run a Diagnostic at the BIOS level to check the physical disk just in case. Everything is good – no bad sector.

We ran the Windows Updates and ensue is up-to-date.

We turn on the Office Updates and ran the updates. Once it is completed, we set to not allow any automatic updates. In the past, we found that allowing regular updates made the search is not working as keep rebuilding the index due to the updates.

We ran the Office – Quick Repair

We ran the Office – Online Repair

As one of the Outlook profiles has PST files, ran the scanpst.exe and found all of them need to be repaired. Managed to repair all PST files. The backup PST files are kept safe on the cloud storage.

Checked the windows.edb file size. The file is located in C:\ProgramData\Microsoft\Search\Data\Applications\Windows. We found the size is around 4 GB in size. In the past, we experienced the size can be up to 50 GB in some cases on another machine.

We narrowed down that the search functionality stopped working only for the Zimbra Outlook profile – the Microsoft Exchange is still ok. This led to looking at the configuration of the Zimbra below.

Once you do the Online Repair/Quick Repair, Microsoft Office reset all the Zimbra configuration. Typical when the Outlook launched, it asked below. It seems it did not add the right registry, therefore, added the registry based on the reference below – Summary of the Registry Keys that ZCO uses.

The registry settings installed by the Zimbra Connector for Outlook (ZCO) have been changed. This might be due to recent Microsoft Office updates. 
ZCO will now launch an external program to reset the registry settings. You might see a User Account Control message box asking your permission. 
Please allow UAC to run the external program. If permission is denied, some ZCO features will not work correctly.


As this blog is written, there is no solid solution as yet and still monitoring the progress.

If you find any findings or tips, please share us on our Dewachat –


  1. Outlook Search Issue –
  2. Summary of the Registry Keys that ZCO uses –



About Author

Valdy founded, a helpdesk and IT Services provider that has taken care of nearly 40,000 customer service requests in the past 15 years - nearly 2,600 per year. He also created the growing - a classified website that has close to 110,000 page views and 9,000+ user visits per month with 61,000+ yearly published ads and 47,000 active registered users. He blogs for the ever-growing, a tech blog that gets around 20,000 impressions per month with 700 clicks and 10 average pages first impressions on Google Search. You can reach him on the Contact Us page, social media links below or

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