Post.php file Issue

Hello Everyone,

I am facing a issue that whenever I add new post and click on Publish to make the page live website redirect to following blank page https://www.columnisthub.com/wp-admin/post.php. Before it was working fine but now I am facing this issue. Can anyone help me to solve this issue.

Looking forward to hear back from you!

The page I need help with: [log in to see the link]