The case of the missing file extension

You’ve received a document, but when you try to open it, the file stubbornly won’t appear! We explain how to fix it.

Our editor-in-chief saw that problem in an Internet cafe‚ in Ketchikan, Alaska and was surprised when neither the manager of the store nor the cruise computer ‘expert’ knew the answer.

As you probably know, Windows ‘knows’ which program to use to open each type of file, there’s little icons next to each file to denote the associated program. This doesn’t happen by magic, each file has an extension after the file name to tell what type of file it is.

For example .. ” Report on Alaska Cruise ” is the file name and as a Microsoft Word document it has the DOC extension. Report on Alaska Cruise.doc is the full file name with a dot separating the two.

DOCX is for Word files as is RTF or DOC, XLSX for Excel worksheets, PPTX for Powerpoint, PUBX for Publisher files and there’s many many more. If you want to see them all go to Windows Explorer | Tools | Folder Options | File Types to see all the associated file types on your computer. These file types are setup when you install the programs.


OK – that’s the basics out of the way and many of you know that. But what happens when it goes wrong?

In the Alaska store the problem was a missing extension, so Windows had no idea what to do with the file when it was double-clicked. The file was saved with a name but no extension. The computer had no idea what to do with the file and the computer showed an error message.

You’re shown a “How do you want to open this file?” box with as list of programs.

That list may, or may not include the right program to open the file. In this case, scrolling down the list will find Word or WordPad (installed with Windows and can also open Word documents).

When you make a document in an Office product it will save it with the correct extension automatically but if you make a file in another way it is easier to make a mistake. Saving a document in WordPad or Notepad can more easily override the extension. Making a document on a Macintosh computer can also mess up the extension when it moves to Windows.


Fixing a bad or missing extension is soooo simple. The ‘one off’ fix is using the ‘How do you want to open the file’ selector, as shown above.

The permanent fix is renaming the file.

In Windows Explorer find the file you want to open. Click on the file name then choose File | Rename , or press F2.

You can then change the filename and extension – to make it viewable in Word just add “.docx” without the quotes at the end. Press Enter to save the new file name.

If you did it right, the icon next to the file name will change to the usual blue W icon for Microsoft Word. Double-click on the file and it’ll open in Word.

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