Latest version lost the ability to preview PDF files

The newest version has lost the ability to preview PDF files. Adobe's Acrobat Pro is installed (the latest version) and all programs including the Windows File Manager have no problems in previewing PDF files. What is going on??

What do you see when you try to view a PDF?

Is there an error message?

Yes, there is an error message: It reads as follows:

"....
This PDF document could not be displayed.

This could mean one of the following:

  • No PDF preview handler is installed on your system.
  • The PDF preview handler is broken (e.g. by other PDF software).
  • The PDF preview handler could not open this particular file.
  • Anti-malware software is blocking access to the document.

Repairing or (re-)installing a PDF viewer is recommended if:

  • File Explorer's preview pane also cannot display the document.
  • The problem affects all PDF documents.

PDF viewers with preview handlers include:

  • Adobe Reader (Reader, not Acrobat)
  • FoxIt PDF Reader
  • PDF-XChange Editor
  • Sumatra PDF (click Options when installing)

......'

Please note that PDFs previews display normally in Windows File Explorer and other File Management programs. The full Adobe Acrobat (latest version) is installed in the computer

Go to Preferences / Viewer / Plugins, configure the ActiveX + Preview + Office + Web plugin there, and see which Preview Handler the PDF extension is assigned to.

Try assigning it to one of the others if you have more than one installed. (Or reset to the defaults if you've already been in there and changed things in the past.)

I don't know if Adobe Acrobat actually includes a viewer. It may do today but it definitely did not in the past, and required Adobe Reader be installed in addition if you wanted to view things.

On newer versions of Windows, there's also a Microsoft PDF viewer which works well. (But avoid the MS PowerToys PDF viewer at all costs. It is worthless. It's possible that's what File Explorer is currently using, as it's blocked within Opus due to being so bad.)