SAXParseException. Pay to fix

No idea what this category title is I am meant to fill in. Nothing I write is found so put in random category

I received a docx file for a job I am bidding on. Spent a day working on a proposal continuing to save it in it’s original format. Next day go to open it to continue working on it and get this

File format error found at
SAXParseException: '[word/document.xml line 2]: Attribute w:cstheme redefined
', Stream ‘word/document.xml’, Line 2, Column 37342(row,col).

It seems that this is a common problem. I have gone through the procesess of following all the guidelines I can find but I have no idea what I am doing. Is there anyone I can send this file to that can fix it for me as it does seem to be possible to do. I can make a small payment. Thank you.

LibreOffice only is the software reporting the error in this case. The file seems to be written by MS Word, and should be assumed to be corrupted in an unknown way. Further details can only (if at all) be investigated with the file at hand. The analysis would require to use an XML editor.

I’d assume that @DigitalMixes edited it using an unknown version of LibreOffice (because they are asking here). And it’s then LibreOffice that introduced such a problem (it used to do that around v.5.0-5.3 IIRC).