Word unable to save document – disk is full error on Mac

Recently I was finishing up a paper for a conference that was pulling two documents, graphics, and data from multiple sources into one Microsoft Word document on my Mac Book Pro.  As I was finishing up and getting ready to do a save, I received a terrifying message:

‘The disk is full trying to write to “Extra Storage.” Free some space on this drive, or save the document on another disk.  Try one or more of the following:
*Close any unneeded documents, programs, and windows.
*Save the document on another disk.’

Now, after having spent some time on this document, this is not the message I wanted to see.  Knowing that I had plenty of space on this relatively new Mac Book Pro, I knew there had to be something else going on.
In this particular case, the problem was that I was saving to the original document type that had been sent to me. A .doc (Word 97-2004) format, and not the newer .docx format.  Since I was pulling in information from a spreadsheet, including the pie charts, tables, and other graphics, it seems Word .doc wasn’t sure how to handle the save.

Once I changed the file format to the newer .docx, it saved without difficulty (dramatically lowering my blood pressure and stress level).

So, if you get stuck with this “Disk is Full” error in Word on your Mac, try changing your file format to the newest version.