PDF files do not appear in dtSearch Desktop/Network after installation of the Microsoft Windows 2026.01 Security Update

Article: dts0246

Applies to: dtSearch Desktop/Network

Last Update:  January 31, 2026

Issue Summary

After installation of the Microsoft Windows 2026.01 Security Update (KB5074109), PDF files appear as a grey box in dtSearch Desktop/Network.  This affects all versions of dtSearch through the current version, 2025.02 and has also been observed in other applications that embed Adobe Acrobat for PDF display.

Reinstalling or updating Adobe Acrobat and changing security Acrobat settings does not resolve the problem.  Because this Windows update addresses security vulnerabilities in Windows so we do not recommend uninstalling it.

Resolution Options

Option 1.   Install the Microsoft 2026-01 Preview Update (KB5074105) (26200.7705).

Installing KB5074105 appears to fix the problem on affected Windows 11 machines.  We have not seen documentation from Microsoft or Adobe addressing this, but we have verified that installing KB5074105 restores embedded PDF viewing.

Note:  This is a Microsoft preview update.  For Microsoft's explanation of preview updates, see:  Preview of Monthly Rollup.

The Microsoft update is available here: 

January 29, 2026—KB5074105 (OS Builds 26200.7705 and 26100.7705) Preview - Microsoft Support

Option 2.  View PDF files as plain text or in a separate Adobe Reader window.

dtSearch has two alternative PDF viewing options that still work: (1) viewing PDF files as plain text, and (2) viewing PDF files in a separate Adobe Reader window.  To select one of these options, run dtSearch and click Options > Preferences > PDF view options.

If you select the option to view PDF files as plain text, you can still click the Launch button or press F8 to open PDF files in Adobe Acrobat or Adobe Acrobat Reader.

Option 3.  View PDF files as formatted HTML (preview/beta feature in dtSearch 2025.02).

dtSearch 2025.02 includes a preview feature that displays PDFs as formatted HTML. This view more closely resembles the original layout but does not support most PDF images and may not preserve exact formatting.

To enable: (1) run dtSearch and close the Search dialog box, (2) press Ctrl+F7, (3) enter "FPDF_1" in the text box and click OK, (4) enable View PDF files as formatted text (preview/beta feature) in PDF View Options.

The formatted HTML display option does not affect indexing so you can turn it on or off as needed without the need to reindex.

Option 4.  Use the dtSearch 2026.01 beta.

The upcoming dtSearch release 2026.01 uses an internal PDF viewer and is not affected by this issue.  For information on the beta test version, please see dtSearch Beta Downloads.

dtSearch 2026.01 requires the Microsoft WebView2 Runtime, which is included on all Windows 11 computers and most computers with Windows 10.  It is available from the Microsoft web site, here: Microsoft Edge WebView2 (the "Evergreen Bootstrapper" download option is recommended).

For notifications of new version releases, you can sign up here: https://www.dtsearch.com/dt_subscribe.html