Can’t see blog posts

When I post a new blog entry and then click view post I get sent to a page with an error message. This also means that if I use the links along the right side of the page to navigate to blog posts, they don’t work. However, if I go to my news page, they are all visible there, but once again if I click on them it doesn’t work.

My website is: https://www.erikaheidewald.com

If you could help me I would greatly appreciate it!