Version Incompatibility. Incorrect file version

I recently reinstalled my Ubuntu and LibreOffice but now when I try to open my saved files I get this error.

Version Incompatibility.
Incorrect file version.

Is there a way that I can convert the files to the more recent Libreoffice Calc? Or am I doomed to have to remake the formats?

What file format (ODS, XLS, XLSX) are the files? Under which application (Excel 2013, 2010, 2007, Apache OpenOffice, LibreOffice, OpenOffice.org) where they created?

I got the same error trying to open a .odt file.

I get the same error, trying to open a .docx file in LibreOffice 4.1.3.2. running in xubuntu 13.10 32 bit. I assume the file was created in a recent version of ms office.