Microsoft has acknowledged an issue triggered by a Windows 10 security update, version 21H2 released on Patch Tuesday December 2021 that causes search issues in Outlook for Microsoft 365.
“After installing update KB5008212, recent emails may not appear in search results,” Microsoft explains in a recently released Office support document.
The company said it is currently investigating this issue and will provide more information and an update as soon as possible.
This new known issue is very similar to another triggered on systems upgraded to Windows 11 causing similar search issues.
Unlike the new bug, these issues started appearing in June 2020 after users started installing early preview builds of Windows 11, which would drop the Windows search index during the upgrade process.
Customers were advised at the time that they could fix Outlook search returning no results by configuring a registry key to disable Windows Desktop Search and switch to Outlook’s search engine.
Once the built-in search is launched, Outlook warns that performance is affected, stating that “Search performance will be affected because a group policy has disabled the Windows Search service”.
Temporary Workaround for Broken Outlook Search
Microsoft recommends the same approach as a workaround until a fix is available for search issues caused by Windows 10 KB5008212 security update.
You must follow the following procedure to disable the Windows Desktop Search service for Outlook:
In Windows, right-click To start upthen select Course. In the To open: box type regeditthen click OKAY. This will open the registry editor.
Find this subkey in the registry, then click on it:
Click on To modify > New > Keyand name the new key Windows Search.
Select the new Windows Search key.
Click on To modify > New > DWORD value.
Type PreventIndexingOutlook for the DWORD name, then press Enter.
Right-click PreventIndexingOutlook, and then click To modify.
In the Value data box, type 1 to enable the registry entry, and then click OKAY.
Quit Registry Editor, and then restart Outlook.
Whenever you want to go back in Windows Desktop Search, you need to disable the PreventIndexingOutlook setting by typing 0 (zero) and clicking OKAY.
Microsoft also recently shared workarounds for other known Outlook issues, including: