In a Microsoft Word 2010 table of contents, you can get the following error:
Error! Bookmark not defined.
To fix the Bookmark not defined error, you should first know a little about how a table of contents works in Word. Word 2010 automatically updates table of contents references as header text moves across pages.
If you get Error! Bookmark not defined, first check that there is actually a title of a paragraph (in heading text) with the name of the bookmark with the error. If there isn’t, delete the row in the table of contents. If the header text is still there but it still says that the bookmark is not defined, this may be because your Word document was edited while Mark Revisions While Editing was turned on. In this case, to fix this simply accept the accept the revisions to the document.