Quote:
	
	
		| 
					Originally Posted by Hayansan  Without making a new epub,if you just open an HTML file and then save it as your new epub.
 In this case, there is no toc.ncx in your epub.
 | 
	
 1. What's your operating system and your Sigil version?
2. Were you working on an epub2 or epub3 book?