Files in Finder not showing previews

The Finder has the option to view file previews and thumbnails, which can be seen both in the document itself as well as the "get info" window for documents. However, for some users, documents that should display a preview are instead showing a generic document icon.

Apple Discussions poster Vintuitive writes:

"I almost always have my folder view set as thumbnail view so that I can see the images without having to open them in Preview. I just realised that I can no longer do that for some reason. Instead of seeing a thumbnail I see large JPG icons. Even loading them into 'Coverflow' doesn't show them, just shows the icons instead."

While this problem might be most noticeable for pictures, it might also occur for other documents as well, including movie files and PDFs. This problem can be caused by several factors, including the changing of the default application used to view the files as well as some Finder settings for previewing the documents. Users affected by this might try the following to correct it.

Fixes

Ensure Finder "Show preview" options are checked If the problem seems to be with documents in a specific folder or on the Desktop, it may be that the view settings for that folder have been reverted. The default options for folders are to have document previews visible, but corruption in the ".DS_Store" file that contains these settings might prevent the previews from being enabled. For the affected folder, users should ensure it is in the foreground as the active window, and then from the Finder's "View" menu select "Show View Options". Then select the option to "Show icon preview" and close the options window.

Change the default application for the item(s) The Finder uses "Preview" to help render certain documents, including image files and PDFs. If users have switched the primary handling applications for these document types to a third-party program, it is possible that this switch could be interfering with the Finder's handling of the previews. Users can try reverting file types back to using "Preview" by getting information on one, and then changing the application associated with the file in the drop-down menu. Then optionally, clicking "Change All..." will ensure the changes are global instead of pertaining to the selected file only.

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