docx file don't open. File format error at SAXParseException

Hello to all!
Last night I finished a big job on a file. docx. I have always worked on libreoffice 5.0 I closed it and shortly after I opened it. Nothing happened particularly in the meantime. but now my file does not open anymore and I get this error message: File format error at SAXParseException: ‘[word / document.xml line 2]: Attribute w: eastAsiaTheme redefined’, Stream ‘word / document.xml’ , line 2, column 270 675 (row, column)
I also tried to open the xml file. it seems that there are all of my content. But I do not know the code and i’m not able to remedy.
Unfortunately I can not even post the file because it is a confidential document.
does anyone have any suggestions for me?
yesterday night I found this post: “” they have my same problem.
At the end someone writes: Was interested, so I investigated a bit more. In the end I removed all 'w:cstheme=“majorBidi” in document.xml and replaced it in the docx. Now you should be able to see everything again.

I also want to do it myself and try to retrieve the file. but I do not know how to do. Can someone help me?
thanks to everybody!

Dupe: Q64973