Windows security blocks every Dropbox file with protected view and disables pdf previews

Question

I have spent literally dozens of hours trying to resolve this and reading existing posts on this to no avail.  Sometime in the last few years, EVERY SINGLE dropbox file (in both my personal and business accounts for the organization I run) is blocked by Windows security.  This means that EVERY time I open a Word/Excel/Powerpoint file, I have to first click the button to allow editing at the top before I can work with it, and ALL previewing of all pdfs is PERMANENTLY disabled due to security risks.  I do not have (and have never had) any files set to "online only". This happens regardless of whether anyone else has ever edited the file.

I have already added all dropbox folders to trusted locations and changed the Windows permissions to stop doing "Mark of the Web", and followed practically every solution I can find listed online for dealing with this issue.  While these changes work if applied to folders outside dropbox (e.g., my downloads folder), they have NO EFFECT on any files in Dropbox folders.

This is ruining my productivity.  It adds endless extra clicks to everything I do (e.g., I edit a file, save it, reopen it seconds later, have to verify that I want to edit it [often after I have already searched, scrolled down, and highlighted something, which means I have to redo all of that after it is editable], and then I can final edit my own file); when I need to review hundreds of pdfs in a folder, I can't simply use the preview pane to quickly view one after the other (something I need to do often).  I need an actual fix that will permanently stop Windows 11 from doing this.  At this point I have disabled core security features in Windows just trying to get this to stop and it still hasn't worked but it has left my computer at much higher risk.

I would appreciate any help in stopping this behavior.

Megan · Answer

Hey there, Claire!

I'm glad we managed to tackle one down!

Since the thumbnails did not change after closing the desktop app, it's possible they might be influenced by third-party software. Additionally, since the preview issues persist while Dropbox is not running, it suggests that the desktop application itself is not directly causing the restriction.

While we look into this further, would you mind trying a couple of quick tests?

-Try moving a few of the affected files completely outside of your Dropbox folder and then back in to see if the behavior changes.

-Try changing one of the sample files to "Online-only" to see how it behaves:

1) Select the file.

2) Right-click and choose Make Online Only from the context menu.

Finally, could you please share the exact Dropbox app version you're using, and its current syncing status? You can find this information by hovering your mouse over the Dropbox icon in your taskbar (next to your Wi-Fi icon).

Thanks a bunch!

Claire W.3 · Answer

@Megan, the answer is complicated.

Quitting dropbox, and then opening a word file that previously gave me the error, the file opens without the error.  Starting dropbox again and the error returns.  Tried this a few times and can confirm same pattern both times. However, that document works in the preview pane both with and without dropbox actively running.

Other word files (that open without the error, both with and without dropbox running, but that were edited by someone else) do not display in the preview pane—and instead give that preview pane error the same as pdfs—regardless of whether dropbox is open or closed.

The preview pane error with pdfs remains, regardless of whether dropbox is open or closed.

Yes, the steps you outlined are the ones I followed (and quadruple checked, since every time I tried to find a solution this is what I was told to do).

I read the protected view documentation you shared, and changing those settings (disabling protected view) finally allows me to open files in Word without getting the error—thanks (other guidance kept telling me to edit trusted locations and not these settings)!  However, I still have the issue with the preview pane not working with dropbox files.

Megan · Answer

Hey @Claire W.3, thanks so much for the speedy reply!

When you quit the Dropbox desktop app and check your files while it remains closed, do you still experience the preview issue and the "Protected View" prompt?

Regarding your mention that you have already added all Dropbox folders to trusted locations, could you confirm if you used the following steps?

-Open the Control Panel.

-Go to Internet Options.

-Choose the Security tab.

-Select Trusted sites, click Sites, and add your Dropbox location there.

Also, have you already reviewed Microsoft's official guidance regarding "Protected View"?