Troubleshooting

Troubleshooting

• First, please check that you're running the latest version for your version of macOS, log out of macOS and back in again and see if the problem remains.

Thumbnails and Previews

If Finder doesn't show thumbnails and/or previews for any "non-native" video files:

• In Finder choose View → Show View Options (⌘J) and ensure that Show icon preview is checked. Otherwise:
• Re-run the QuickLook Video app. This reminds Finder, QuickLook and Spotlight that the app and its extensions exist in case they have forgotten.
• Under System Settings → General → Login Items & Extensions find QuickLook Video near the bottom. Press the ⓘ button next to it and uncheck and re-check the "Media Extensions" settings:
  
  • On older versions of macOS the settings are Video previews and Video thumbnails under System Settings → Privacy & Security (scroll to the bottom) → Extensions → Quick Look.
• In the QuickLook Video app press Refresh. This tells QuickLook to clear its thumbnail cache and then restarts Finder to make it refresh its thumbnail cache.
• You may need to log out and back in again.

If Finder doesn't show thumbnails or previews for some "non-native" video files:

• This app adds support to macOS AVFoundation for a wide range of file formats and codecs, but AVFoundation cannot be made to support all formats, codecs and codec profiles.

If Finder doesn't show thumbnails or previews for some "native" video files:

• macOS doesn't allow this app to handle displaying thumbnails or previews of "native" file types, including .mp4, .m4v, some .avi, .dv, some .mov, .mp2, .mts, .ts, .vob. If macOS can't display them then unfortunately this app can't help.

Cover Art

• Use File → Cover Art to add, replace or remove cover art.
• If Finder doesn't show the thumbnail as you expect or if the resulting file is not playable you may have better results with a specialised editing tool such as Subler for .mp4/.m4v files, or MKVToolNix for .mkv/.webm files.

Metadata

If Finder doesn't show metadata for "non-native" video files:

• If the problematic files reside on an external or remote volume check that you have write access to the volume - see Change permissions for files, folders or disks on Mac - and that you don't have a hidden file named .metadata_never_index at the root of the volume.
• Ensure that you haven't prevented Spotlight from indexing the folder or volume containing the files - see Prevent Spotlight searches in specific folders or disks.
• Spotlight can be slow to notice new plugins. Under System Settings → General → Login Items & Extensions find QuickLook Video near the bottom. Press the ⓘ button next to it and uncheck and re-check the "Spotlight" setting:
  
  • On older versions of macOS you can check by typing mdimport -L in the Terminal and checking whether "/Applications/QuickLook Video.app/Contents/Library/Spotlight/QLVideo Metadata.mdimporter" is listed.
• If you see a message in the QuickLook Video app about high CPU and disk usage then Spotlight has found the extension and the app has asked it to re-index video files. Re-indexing happens in the background so it may take a few minutes before you can see the metadata in Finder.
• Once Spotlight has found the extension:
  • You can force it to re-index video files by copying the following, pasting in the Terminal app, and pressing Enter:
    mdimport -r "/Applications/QuickLook Video.app/Contents/Library/Spotlight/QLVideo Metadata.mdimporter"
  • Alternatively, you can force Spotlight to re-index all the files in a specific folder with:
    mdimport -i /path/to/folder

External volumes

Deleting files

• You can't delete a file while Quick Look is thumbnailing or Spotlight is re-indexing it.

Unmounting

• You can't unmount a volume while Quick Look is thumbnailing or Spotlight is re-indexing any files on it.

In both cases unfortunately you'll have to be patient until Quick Look and Spotlight settle down.

Thumbnails

If Finder can't store its thumbnail cache on an external volume it will regenerate thumbnails every time you attach to the volume. This can happen for several reasons:

• The external volume is formatted as "MS-DOS (FAT)" or "ExFAT". Please backup and reformat your external volume as "Apple File System (APFS)" or "Mac OS Extended" if possible (which will give you better performance under macOS in general).
• You have told Finder not to save the .DS_Store files that it uses to cache thumbnails. You can check this using the Terminal app:
  defaults read com.apple.desktopservices DSDontWriteUSBStores or
  defaults read com.apple.desktopservices DSDontWriteNetworkStores
  Both will show 1 if you've disabled the .DS_Store files, and 0 or The domain/default pair ... does not exist if you haven't.
  You can re-enable the .DS_Store files with:
  defaults write com.apple.desktopservices DSDontWriteUSBStores -bool FALSE and
  defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool FALSE

Reporting an issue

• From the QuickLook Video app's Help menu, choose Report an Issue.
• Drop any problematic file and press Send.
• Give the new Issue a title, describe the problem and press Submit new issue.