CMS简单无法编辑页面

I'm currently trying to slowly update our very outdated CMS made simple installation. But have run into an issue updating from 1.11.4 to 1.11.6. Meaning that I am unable to create or edit pages. When I try to edit or create a page it shows a menu without styling with links to the pages on my site.

This is what shows when trying to edit or create a page.

Has any one got an idea how I solve this. I am trying to solve any issues that appear before updating to the next version so it is easier to see when it appears.

Make sure that all css and javascript files are properly linked and inspect the element in your latest browser and check for any errors and try to fix it... It will sure work. I think some CSS or Javascript files are missing.