Try to re-enter an ODS file that I've worked on since June

Got an error message. Error was found on sub-document content.xml at 2,91370 (row,col). How do I correct error?

Have a look at this post for possible solutions. If you are not comfortable doing what is suggested there, post your document on a file sharing host and edit your question to provide a link to the document; someone may be able to help.

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