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Finder preview – just universal thumbnail (for JPG, PNG, PDF, etc)

Hi all,


I'm experiencing another case of a situation, the thumbnails for documents (images, pdfs, etc.) are no longer showing, and the display is a universal generic icon.

I have a iMac 27", 2017, running on the latest Mojave (10.14.6) –

Everything was moved on this iMac from Time Machine backup.


I have tried everything from the list below:

    • I have tried deleting com.apple.finder.plist several times, problem persists
    • Finder's "show icon preview" is on; I have tried unchecking and re-checking the box, problem persists
    • I have created a Test user and downloaded an image- the thumbnail WORKS in the test user
    • The main user on my computer has permission to read and write
    • I have put my computer in safe mode, problem persists
    • Removed apps from launching when booting up Mac, problem persists
    • Reset NVRAM, problem persists
    • Relaunched preview, problem persists


The problem persists though.

I've also tried everything from similar threads:

Finder preview thumbnail not displaying (… - Apple Community


In addition, I've also tried another user with admin rights and moved some of affected documents to Users/Shared, but without any progress


Thanks for a tip – it's really annoying, to not be able preview of images or PDFs


[Link Edited by Moderator]

iMac, macOS 10.14

Posted on Jul 2, 2022 4:13 PM

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Question marked as Top-ranking reply

Posted on Jul 3, 2022 3:53 PM

I've got it!

It was something from Google Drive, that blocked the system-wide icons generating!


After reinstalling Google Drive and allowing it to use System software and after the following restart are all the icons back!

I've noticed in an discussion forum, that some people had icons blocked by Dropbox and somebody mentioned Google too, but I didn't pay attention to it.


All in all, thanks for your assistance, BDAqua, you've taught me some new things.


Take care, pal!


Greetings from Czechia, EU

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11 replies
Question marked as Top-ranking reply

Jul 3, 2022 3:53 PM in response to BDAqua

I've got it!

It was something from Google Drive, that blocked the system-wide icons generating!


After reinstalling Google Drive and allowing it to use System software and after the following restart are all the icons back!

I've noticed in an discussion forum, that some people had icons blocked by Dropbox and somebody mentioned Google too, but I didn't pay attention to it.


All in all, thanks for your assistance, BDAqua, you've taught me some new things.


Take care, pal!


Greetings from Czechia, EU

Jul 3, 2022 4:25 AM in response to BDAqua

Thanks BDAqua,


Safe Boot was one of the first measures, I've tried (as shown in the list in the beginning of this thread).


I've performed the Terminal commands from your response with results as follow:

    • The initial problem with generic icons persists
    • All (or at least most of) the Apple apps have lost their specific icons (Dock and Last items menu) and were replaced by generic apps icon
    • After restart they reappeared, except Messages.app


The strangest thing is, that – from the very beginning – there are a few icons, that have kept their image content thumbnail (all of them JPGs), but the rest keep their app generic icon.


I've migrated system from a backup in dozens times, but this is the first time, I'm experiencing the icon problem.

Jul 2, 2022 4:54 PM in response to Radan Behoun

Hi there...


Safe Boot, (holding Shift key down at startup), does the problem occur in Safe Mode? Could take 10 minutes.


Safe mode attempts to repair Disks & clears lots of caches & loads safe Drivers, & prevents loading of 3rd party extensions, so if Safe Mode works try again in regular boot.


Manually Rebuilding Spotlight via Terminal

If the aforementioned Spotlight control panel approach doesn’t spur a reindexation of the drive, you may need to initiate it manually through the command line. Open Terminal and use the following command string to do so:


sudo mdutil -E /

This basically asks for temporary super user status, which is why Terminal may ask you for your password (it may not if you’ve used a sudo command recently or are already logged in as a super user or root. The command asks the unix tool mdutil to reindex the spotlight database for everything on the computer, including external drives, mounted disk images, etc.


sudo mdutil -i on /


Rebuilding a drive index can take a long time, so be prepared to wait whether you do it through the System Preference panel or the command line.


If still need be…


Open Terminal and run each of these one at a time


/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user


sudo /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -seed -lint -r -f -v -dump -domain local -domain system -domain user -domain network


killall Dock


sudo mdutil -E /


sudo mdutil -i on /


Rebuilding a drive index can take a long time, so be prepared to wait whether you do it through the System Preference panel or the command line.

Jul 3, 2022 11:10 AM in response to BDAqua

Hi BDAqua,


in my original post, I've written:

In addition, I've also tried another user with admin rights and moved some of affected documents to Users/Shared, but without any progress.


In other words – it doesn't work in a new account either.

I also tried to copy other files – it's the same – just generic thumbnails. When I create a new document (e.g. screenshot or a duplicate of existing image) it's got also just the generic preview.

Those few, that already had the right thumbnail, keep it also in another user.


So it seems to be that the problem is on system level.

I've even reinstalled the system in the meantime, but it didn't changed the crucial behavior. It's probably somewhere in the system QuickLook library file.


I need to stay on Mojave, because of Adobe CS6.

Jul 3, 2022 2:55 PM in response to BDAqua

Thanks for a suggestion,


I remember Graphic Converter (GC) from the old days of Mac OS 7–9 in mid/late 90's.

I tried it, but it will not help in this case

– in GC everything looks OK

– in Finder, everything looks not OK, even the newly converted files by GC have just generic icons

– restart will not change anything

This is not a solution, especially for PDFs


I don't know what's wrong, that system will override even the re-generated stuff from GC.

Finder preview – just universal thumbnail (for JPG, PNG, PDF, etc)

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