Linking not set up correctly in PG?

I am creating and redoing a site in PG but when I loaded it up online, it creates hashtag error on the links. My host said:

My best guess is there is some kind of file linking/pathing issue with the HTML code.

Example https://diamondseller.com/index.html but when you select those pages the link becomes https://diamondseller.com/index.html#.

I would look into possible errors within the code of index.html.