How do you open files that say "The index.xml file is missing"?

Make sure you are using the latest version of Number to open the file. When you experience this problem, check the version of Number by selecting the menu item "Numbers > About Numbers" and make sure the version is 4.x. If it isn't, then close Numbers and open the folder Applications, then make sure you open the right version of Numbers

Take a look at this tip:

Need newer version of Numbers to open file

Hi jartimms,

You have two versions of Numbers on your machine. Numbers '09 (Numbers 2) is trying (and failing) to open a Numbers document saved in a newer version. See this User Tip by Wayne:

Need newer version of Numbers to open file

Please call back with questions.

Regards,

Ian.