Windows 11 Pro no longer shows preview of pdf files

I was on my Win11 Pro Notebook when I posted about the Preview icon earlier and now have checked my Win11 Home Notebook and Win11 Home Desktop, they also have the icon but neither one has Adobe anything installed.

My Win11 Pro Desktop does have Adobe Acrobat 9 and Lightning PDF installed but does not have that icon, still have to choose Preview pane from the View item, only inconvenience is just one more click.

For those who keep saying to select the file first; click the show preview, etc, etc, I am well aware of what should work and I have been struggling with this problem ever since Microsoft update 3 or 4 months ago.
I had previews, and used that function a lot before the update then previews were no longer available. It is nothing that I did and I totally blame the update. I have been using, and fixing computers since the ZX80 in the early 70s. (remember that wedge with 16k memory?)
Yesterday in (in desperation) I uninstalled 5 updates (only 5 available), rebooted the system and it promptly reinstalled updates despite the setting set for no updates.
I bet the Mac doesn't have this problem!

Hi, @stevethetrumpet and everyone else.
I came across the forum looking for, I guess, a solution to the problem you described in the first post. I completely understand your frustration, both with the problem and with some "helpful" answers, and if you remember the ZX80, then even more.
I completely agree with your assumption that it must have been because of an update, but for which app, I wouldn't dare to guess. I was disappointed with the advice I found here, but I'm stubborn, so I moved on. After searching and reading, I decided to try something. I checked on two computers with the same problem (both Windows 10), and it worked on both. I then decided to go back to the forum and register to write a solution, whether it was still needed. Also, I don't know if it works on Windows 11 or not.
First, there is a reg key at HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers which might look like this (without the highlight, of course):

Then, there is another one at Computer\HKEY_CLASSES_ROOT\.pdf\ShellEx\{8895b1c6-b41f-4c1c-a562-0d564250836f} in which, at first, there was a key of Adobe PDF Preview Handler for Vista (listed at the 3rd place from the bottom).

Since I tried (as you did) every reasonable advice I could find with no avail, I concluded there must be some mismatch between OS and Adobe (I have previous experience with an older Canon scanner and HP printer and Windows 10, which both worked fine with Windows 7). So, what I did was I manually proclaimed Microsoft PDF Previewer to be the default Preview Handler by copying the highlighted key to the .pdf class key (result shown in the image above).
And after that, voila, the PDF preview starts to work again.
Now, why and how, I don't know, but I did it, and it works. I restarted both machines, and it still works. What will be after the next update from whoever, who knows?

@Dado
Will the PDFs scroll in the preview pane?

Hi @Edwin. Yes, with scroll.

Dado said:

Hi @Edwin. Yes, with scroll.

Click to expand...

Hmmm..., I have a reasonable suspicion that Adobe registers it's own .dll as a preview handler, cuz nothing works here with Sumatra!

Like I said, I wouldn't venture a guess. Maybe so, but for some reason, it doesn't work. Perhaps they forgot how to write a DLL (), or there is something else. What bothers me is the time needed for the reaction while we struggle with the stuff.

Hi @Edwin. Further to your suspicion, a few minutes ago, I watched the installation of the Adobe Reader update, and after it was done, I could not preview PDF documents again. I checked the registry and found it re-registered itself as the initial pdf preview handler. Perhaps it does that because of the settings, but some communication between Adobe Reader and Windows is not working as it should.

Dado said:

Hi @Edwin. Further to your suspicion, a few minutes ago, I watched the installation of the Adobe Reader update, and after it was done, I could not preview PDF documents again. I checked the registry and found it re-registered itself as the initial pdf preview handler. Perhaps it does that because of the settings, but some communication between Adobe Reader and Windows is not working as it should.

Click to expand...

Go figure!
That's technology for ya!
No biggie though, I don't need the feature that badly, but, thanks for the heads up!

Well, I'll be damned!
I just updated my W10 machine to W11 and it's working!!!

I see the preview after in 'view' select preview pane.
select 'content' also shows the preview.

I do NOT have Adobe installed.

I get it in 22621.3155 but not on the Canary Build!

Edwin said:

I get it in 22621.3155 but not on the Canary Build!

Click to expand...

I am on that version too.

I have the same problem on 23H2 build 22631.3155.
For me, the only files for which the previewer works are .jpg files.