Next/Previous Page Blank & Error

Okay, there are several next page links in WordPress.

* Next and Previous Posts
* Next and Previous multi-post pages (front page/categories/archives/search)
* Next and Previous pages of a single post that uses <!--nextpage-->

Here is info about them:

https://codex.www.ads-software.com/Good_Navigation_Links
https://codex.www.ads-software.com/Next_and_Previous_Links
https://codex.www.ads-software.com/Styling_Page-Links

Part of your problem might be with your permalinks structure, but then I ran a validation check on that page and I think if you clean up those, you might fix some of the problems. There are a few problems there to pour through. Some are related to ads, but there are others in there.

If you turn off permalinks, do you still have the problem? rename your .htaccess file and see if it cleans it up. If it does, then the problem might be there. If it doesn’t, then let us know.