>while saving admin cms pages 
getting 404 not found page

in magento 2

already permission for 
      
    pub/media 777
    var  777
how i can solve this 

i'm using magento 2.1.11


Edit1:

 

>  I created new cms page when i add text and i saved that  it's working

> **if i add any files(image) then i save that i'm getting 404 page error not found**

pub/media permissions

[![enter image description here][1]][1]

 


  [1]: https://i.sstatic.net/QGrJb.png