When I try to browse an image in the admin back-end to upload blog image, I get a blank page with error: "You don't have permissions to browse server."
This is a permission related issue where PHP has insufficient rights on the folder where it tries to store the session files.
Since, as it appears, you are using a proper hosting service you should ask your host to rectify this issue.
Alternatively, you may try doing it yourself as shown in the following article -
https://tutorialspots.com/php-how-to-fi ... -3402.html
Hope this helps.