Category Archives: nginx

phpMyAdmin – session_start(): open(SESSION_FILE, O_RDWR) failed: Permission denied (13)

phpMyAdmin – Error

Error during session start; please check your PHP and/or webserver log file and configure your PHP installation properly. Also ensure that cookies are enabled in your browser.

session_start(): open(SESSION_FILE, O_RDWR) failed: Permission denied (13)

Try to chown /var/lib/php/session/ with the user who is running httpd.
In my case it was nginx.

chown nginx: /var/lib/php/session/

nginx – failed (13: Permission denied)

In a fresh CENTOS, while installing & testing nginx i’v faced the following error..

2019/10/10 17:54:11 [crit] 18960#0: *1 stat() "/home/www/html/index.php" failed (13: Permission denied), client:, server:, request: "GET /index.php HTTP/1.1", host: ""

This is how I’v solved.

chcon -R -t httpd_sys_content_t /home/www/html/

More readings

/.well-known/acme-challenge/ – 404


1 renew failure(s), 0 parse failure(s)

 - The following errors were reported by the server:

 Type: unauthorized
 Detail: Invalid response from
 "<!DOCTYPE html>
 <html lang="en">
 <title>404 Page Not Found</title>
 <style type="text/css">

::selection{ background-color"

To fix these errors, please make sure that your domain name was
 entered correctly and the DNS A record(s) for that domain
 contain(s) the right IP address.

Try to add the following, inside server{}, on user nginx domain configuration..

location /.well-known/acme-challenge/ {
    try_files $uri /dev/null =404;

And reboot nginx… 🙂

letsencrypt renew – 404 – Detail: Invalid response


letsencrypt renew output

Type: unauthorized
Detail: Invalid response from

nginx error log

66.133.XXX.XXX - - [11/Feb/2017:09:33:20 +0100] "GET /.well-known/acme-challenge/WLpdvugG3YzC53RTrZMJcYWsRqcj64vWLw43HNBkMN6 HTTP/1.1" 404 247 "" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +"

“Somehow” my domain root has changed.
I had to take a look at /etc/letsencrypt/renewal/ and fix some paths… 🙂


Warning: Unknown: open(/var/lib/php/session/ O_RDWR) failed: Permission denied (13)

I was getting the following error on a *fresh* CentOS…

Warning: Unknown: open(/var/lib/php/session/sess_isu2r2bqudeosqvpoo8a67oj02, O_RDWR) failed: Permission denied (13) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/lib/php/session) in Unknown on line 0

This will do the work…

chown -R nginx:nobody /var/lib/php/session && chmod -R 770 /var/lib/php/session