My Macbook has suddenly stopped generating preview icon of all file types. So all files are now replaced by their respective generic file type icons (see picture attached). Moreover, when I quicklook any file, the preview appears corrupted.

I have not updated any software recently, nor have I modified any file systems.

Any help would be much appreciated!

Corrupted Quicklook and Icons

  • 1
    First thing I'd try would be to run "sudo qlmanage -r" in a terminal, which will reset the QuickLook subsystem.
    – calum_b
    Feb 29, 2016 at 11:16
  • Cool... I'll add it as a proper answer then, didn't think it'd be that easy :)
    – calum_b
    Feb 29, 2016 at 13:07
  • This worked for me: apple.stackexchange.com/q/436449/415526
    – monotom
    Feb 4, 2022 at 21:20

3 Answers 3


Per comment under original question, first thing I'd try (which turned out to be the solution) would be to run sudo qlmanage -r in a terminal, which resets the QuickLook subsystem.


Merely running sudo qlmanage -r did not fix this issue for me.

For me, the direct cause was QLStephen.qlgenerator. The issue happened overnight and I suspect Apple's latest silent OS X update may have played a part in this. I removed the plugin the same way I installed it (Homebrew); if you manually installed it, simply drag it out of the plugins folder in your Library and run sudo qlmanage -r

Thong.qlgenerator also caused an issue for me (PNG only showed as an icon).


From MacRumors:

  • Open Activity Monitor
  • Search for a process called `com.apple.quicklook.ThumbnailsAgent``
  • Force quit the process
  • Force quite Finder (from the Force Quit menu)

enter image description here

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