Please note that, despite some superficial similarity of the error message, the problem in your file is very different from what was in the document of OP. In your document, the word/document.xml contains a recurring erratic pattern like
<w:del ...><w:sdt><w:sdtPr><w:id w:val="..."/></w:sdtPr><w:sdtContent></w:del>...</w:sdtContent></w:sdt>
where w:del is positioned erroneously - it starts before w:sdt starts, it ends before w:sdtContent and w:sdt end - but after w:sdtContent starts.
It obviously related to tracking changes; and possibly the proper placement would be around the whole w:sdt; or maybe around w:sdtPr. Hard to say. But given the count of the problematic pieces, I can’t invest into rectifying it manually, and testing the different options. Maybe my explanation could help you do that yourself.
It would be very important to get a sample document (ODT) that would break like that when saved as DOCX - only then we could reproduce, find the error in code, and fix.
