Using Unoconv to convert .xls to .xlsx on Centos 6.3

Hi, if LibreOffice has the ability to save documents as .xlsx why can’t Unoconv?

Currently I’m having to convert excel files by calling “soffice.bin --headless --convert-to xlsx somefile.xls”, but this give me a issue if two or more separate processes are trying and start soffice.bin at the same time.

Here’s the Unoconv homepage and bug tracker:

Bug #1 mentions xlsx export support:

What version of LibreOffice are you running? What version of Unoconv?
What happens if you try to convert a file to xlsx using Unoconv?