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PDF-XChange preview handler hangs


Windows 10, PDF-XChange Editor Pro v7.0, Wordperfect X8, Word 365 ... viewer hangs when attempting to view files, forcing resort to kill via Task Manager. This may be coincident with upgrade to DOpus 12.8, or other system change lost in the mists of time.

How might I (a) Troubleshoot the cause, (b) Flip a switch to solve the issue?

Thanks in advance for excellent support of excellent, strategic product.

Bruce Chitiea
SafeSectors, Inc.
Claremont California USA


Which file format(s) do you have the problem with?

Is File Explorer able to view them OK in its viewer?


There appear to be two, most-likely unrelated, issues here:

1. PDF files (PDF-Exchange Editor Pro v7.0 installed)
- An attempt to view any PDF file locks up DOPus, forcing a Task Manager [End Task].
- File Explorer fails to view PDF, but does not lock up.

  1. WordPerfect WPD files. (Corel WordPerfect X8)
    • File Explorer opens WPD files without issue.
    • A little harder to pin down. DOPus opens WordPerfect files ... for a while.
    • After viewing a WPD file, a WordPerfect "stub" remains active as a Background Process when the DOPus Viewer closes. The process is additive: a stub remains after each view, so the list can become quite formidable, unless I open Task Manager and manually terminate these stubs. When an (as yet) untested number of stubs collect, DOPus hangs when attempting to open the next WordPerfect file.


You probably need to (re-)install a PDF viewer, one which includes a preview handler.

PDF-XChange has a viewer but I don't know if their Editor Pro package includes it, or if it's a separate thing.

I would get it working in File Explorer first, then see if the problem is solved in Opus, as it probably will be at that point.

You can also see which viewer(s) Opus is attempting to use for PDF files by looking at the ActiveX + Preview + Office + Web viewer plugin:

(None in my case, as I don't have a PDF viewer installed, but it will be listed there if one is.)

Sometimes you may have multiple viewers and one takes over the extension from the other. The last you install usually wins. You can move the extension around in the plugin config window shown above, but it only affects Opus, not other software that may use the same viewer (File Explorer, Outlook).

On older versions of Opus, we would also try to view PDF files via Internet Explorer. If the Internet Explorer line in your config window has the pdf extension on it, you may be using an old version. Unless you added it back to that line on purpose. (If so, the IE-based viewer is now crashing. File Explorer won't use IE-based viewers, which may be why it is failing instead of crashing.) The Defaults button at the bottom left will reset everything to normal.

Modern PDF viewers will appear in the Preview Handlers section at the top.

Viewer Pane problem with pdf files

Thank you for your detailed, cogent response.

  1. File Explorer still declines to view PDFs, but does not crash.

Note: After each DOPus configuration change discussed below, DOPus was closed, then reopened for testing.

1.Elimination of a PDF association with Internet Explorer (32) did not affect the DOPus outcome (Note that "Directory opus ActiveX Proxy" remains in the Task Manager Background Processes list following DOPus termination. )

  1. There are two (2) entries for the PDF-XChange Preview Handler in the ActiveX ... list. The first of the two (checked) lists the ".pdf" extension. The second of the two (also checked) lists no extension.

a. Unchecking this second instance does not affect the undesired outcome.

b. Adding the .pdf extension to the second instance removes it from the first instance. This does not affect the outcome. Unchecking the now-blank first instance does not affect the outcome.

I will explore Tracker Software's resources on their Preview Handler and report back.

Thank you, Bruce Chitiea SafeSectors, Inc.


SOLUTION. The PDF viewer hang issue resolves easily

PDF-XChange Editor pro v7.0 includes a detailed configuration facility within the path File > Preferences > File Assocations form.

  1. Set "Register NP-plugin for other browsers" to "Yes"
  2. Set "Preview Handler for PDF files" to "Yes"
  3. Set "Thumbnail Handler for PDF files" to "Yes"
  4. Hit [Apply]
  5. Restart the machine.

I had performed steps 1-4 previously, without affecting the outcome. The Restart did the trick. Thank you for your help! Bruce Chitiea, SafeSectors, Inc.