Why can't I save my odp.?

When I try to save it as and ODP. it tells that here is a writing problem. I’m using version Never happend to mer before. I’ve even saved this odp before. Just made some minor changes and then appareantly I can’t save it. I made a copy and saved it as PPTX… If someone has Microsoft PowerPoint will they be able to open my file if I save it as PPTX?

Are you able to save with another name?

If you need to share your file with Microsoft PowerPoint users, better save to PPT. And in any case, upgrade LibreOffice to 5.x, as there have been implemented quite many improvements in terms of compatibility.