If File Explorer Preview for PDF is not working or displaying correctly and shows ‘INDEX OF…’ under Network folders, here's what you need to do.

Don’t like to wait for programs to boot up when you’re looking for a specific document? With the right tools, you can preview a variety of files in Windows 10 without opening their applications.

File Explorer in Windows 10 and Windows 11 comes with its own preview pane that can display certain types of files. You can also turn to Microsoft's own PowerToys utility.

Given how limited the preview pane already feels in Windows 10, even adding just two more file types feels like a huge improvement.

But in my tests, setting Adobe Reader as the default program robbed PDF Preview of the ability to show thumbnails, although it could still use Windows Explorer’s preview pane.

However, the Preview pane isn’t enabled by default. In Windows 10 and 11, you can enable it by opening File Explorer, clicking the View menu, and selecting Preview pane.