403 Forbidden

I get the following message when i try to upload content from summernote editor with special character.
This works fine on my local computer and other web hosting portals.

403 Forbidden
You don't have permission to access /add-news/ on this server.

My Php version is 7.2.10 and my mariaDB version is 10.1.41

I used cake php3.7 to build this website.

Please what could be the problem?

check mod _security

Thank you so much, it worked!