Missing file extensions causing errors with files opening in OS X

OS X by default hides file extensions on files, so users may be confused when they have files that are not recognized at all by OS X and hence do not open.

One source of the error is the fact that the file in question has no extension at all.

To check for a single file and its missing extension:

  1. Right-click a file and select Get Info. If you have a Mac with a one-button mouse, hold the “Control” key and click the file.
  2. Click the triangle next to Name & Extension. The text field will display the full file name and extension.
  3. Click inside the text field and use the “Delete” key to remove the original file extension.
  4. Type the desired new file extension and close the window.