word compatability

I have just found out that all docs made in Libre over the past year cannot be opened in Microsoft Word. Docs before then open OK. Error message ’ The file shop’*’ cannot be opened because there are problems with the content’ - details:-’ The file is corrupt and cannot be opened’.
I have upgraded to but still the same.

Which LibreOffice Application are you using, which version of Office are you testing with, and are you using the new Microsoft formats (.docx, .xlsx, .etc), the old ones (.doc, .xls, .etc) or the OpenDocument formats (.odt, .ods, .etc)?