This is the first time I ask a question, my concern is this.
In order not to prolong the problem, I will show more relevant fragments
First of all, you have to put the beginning of the file index.php labels to be able to use the sessions, without which we could not use them.
<div class = "alert alert-=$_SESSION['type'];?> fade-show "unusable by the alert" role = "alert"> =$_SESSION['message'];?>// destroys the session when closing the alert not to be refreshed when the page is refreshed, the session is kept and therefore the message identical// form to add a note that sends the data via POST to check in the file save_task.php
// the data is loaded dynamically with the help of JS, with XMLHttpRequest (); title Description Creation date Edit Remove