Any advice needed

I started a new amazon affilaite website a few days back but got some major issues with this website. The last 3 websites I've done was made exactly as the new one. Same theme, same plugins, same structure just different content.

The problem with this new website is whenever I try to post something new and I try to preview it it shows Oops! That page can’t be found.
This only happens when I put in a image using the text editor of the product or a buy now button.

I've been struggling a few days to get to the bottom of the issue but still nothing is helping.

I've changed plugins.
I've changed themes
I've deleted the old wordpress and reinstall wordpress

Any other advise to what the problem could be.