PHP file upload process?

Question

PHP

It is necessary to display the file upload progress via PHP
session.upload_progress.enabled - enabled, checked. All session.upload_progress settings are standard.
I did everything as it is written here habrahabr.ru/post/136974
Downloaded the finished version from here adobkin.com/blog/2011/07/25/767
Does not work. When uploading a file and passing PHP_SESSION_UPLOAD_PROGRESS, the progress variable is not written to the session. What could be the problem?

Answer 1

Session not initialized? session_start(); what does it return?
Sessions not opening on the server? (Or is the lifetime not long enough for the operation?)
In which browser? No difference?