Opening .xls file with Numbers

Question

I saved a spreadsheet from Numbers '09 version 2.0 in .xls format and then tried to open it, but Numbers won't open it because off a reported problem with the plug-in to do that, "SFCompatibility plug-in." This used to work, I think. Perhaps the latest operating system update messed it up. (I have OS X 10.8.5.) Software update says there is no update for any of my apps. My Numbers software is in Applications/iWork '09.

Answer 1

I was not "fooled by Excel's ability to recognize the file format and apply the correct converter automaticallY"
What i mean is some people will export as a text file, but change the file extension to xls to force it to open excel when double clicked, and excel will open it just fine. Converting as it goes automaticaly and not even asking you any questions or putting up any errors.
I know because i just did it to validate my statement (I am working at a Windows machine at the moment), and it worked fine. Even though the file was actually a tab delimited file, with an XLS on the end. If excel was strict, it would have looked for a Binary XLS file and rejected the file.
This does NOT work with XLSX formats. You will get an error that its not formatted correctly. So if excel was able to recognize file formats and apply the correct converter automatically. they removed this ability in 2007+, only leaving it as legacy functionality.
Your statement would be accurate for plain txt files. But excel is NOT ablel to ID the format automatically.
Try saving a comma separated file with a  TXT extension, then try to open it by selecting "files of type" All files, in  an open dialog. It will start the converter for text files but will ALWAYS suggest Tab delimited. never the proper format if anything else. (we use Pipe | delimeted very often at work)
thereby I present you the possibility that it is you that has been fooled by Excel into thinking it knows what its doing
Jason