Incomplete search results may occur in Outlook when a PDF iFilter is installed

  • Article
  • Applies to:
    Outlook 2019, Outlook 2016, Outlook 2013, Outlook for Microsoft 365, Microsoft Outlook 2010, Microsoft Office Outlook 2007

Original KB number:   2925203

Symptoms

  • When you use instant search in Microsoft Outlook, you receive a message that states No matches found or you receive an InfoBar message that states Search results may be incomplete because items are still being indexed.
  • If you check the status of indexing, you see there are still items remaining to be indexed in the Indexing Status window.
  • When you review the events in the application event log, you see items with the following parameters:
Event ID Source Task Category Description
10023 Search Gatherer The protocol host process <PID> did not respond and is being forcibly terminated {filter host process 6104
10024 Search Gatherer The filter host process <PID> did not respond and is being forcibly terminated.

Cause

This problem occurs when a PDF iFilter stalls the Windows Desktop search indexer, causing frequent reindexing of Outlook items.

Resolution

To resolve this problem, update any applications that offer PDF file functionality with the latest patches. Then, follow these steps to rebuild the index.

  1. In Control Panel, select Indexing Options.

    If Indexing Options does not appear in Control Panel, type Indexing Options in the Search Control Panel text box, and then select the Indexing Options search result.

  2. In the Indexing Options dialog box, select Advanced.

  3. Select Rebuild.

  4. Select OK in the Rebuild Index dialog box.