Why aren't session files saved?

Question

PHP

Previously, everything was fine on the site, but now session files are not being written. I couldn't find the cause of the error myself.

When assigning an array element to $_SESSION on the page, the variable is used normally, but the file in /tmp (according to phpinfo) does not appear. Accordingly, when moving to another page, there is no data in the session. The rights to the folder - 755. Additional adding session_start(); at the beginning of the page code and session_write_close(); didn't help at the end. The error is repeated on different computers and in different browsers.

Site on wordpress. Hosting support wrote a reply.

Answer 1

1. no write permissions. try to explicitly write from the script to /tmp and see what happens
2. no disk space
PS native $_SESSION is evil.
PPS wordpress absolute evil

Answer 2

permissions on /var/lib/php/session must be writable for the user that the web server is running as.

Answer 3

df -h
df -i