Tinymce 4.9.8 upload image

By looking at your code, most probably the image location returned in the JSON object does not exist, because you are building it from $imageFolder, which uses a relative path. 

To the point, instead of this

PHP Code:

$img = [
         'location' => $filetowrite
       ]; 


try to use this:

PHP Code:

$img = [
         'location' => base_url('public/blog_img/') . $temp['name']
       ]; 


If it still does not work, consider installing Fiddler (or some equivalent HTTP traffic monitoring tool) to debug what's going on. This will let you see the exact HTTP response that gets returned.