title: Cant open session in PHP
body: <p>I am currently struggling with a problem with one of my companies web applications. In the production environment we have a problem in which macbooks cannot create a session in one application when they're having a session in the other application. I pretty much narrowed down the problem but I am yet to find a solution.</p>
  
  <pre><code>PHP message: PHP Warning:  Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0" while reading upstream, client: 80.113.209.4, server: example.com, request: "GET /api/config/routes?route=%2Fauth%2Flogin HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm/example.com.sock:", host: "example.com", referrer: "https://example.com/auth/login"
  </code></pre>
  
  <p>Now when I go to the  /tmp directory I am starting to see where things go wrong:</p>
  
  <pre><code>-rw-------  1 app1 www-data     0 Apr 20 10:43 sess_5tqsb9cbohto3anslkfiqm9uq6
  -rw-------  1 app1 www-data     0 Apr 20 10:41 sess_8ecc8s1ipbb0h1l4b342nfqph2
  -rw-------  1 app1 www-data     0 Apr 20 10:43 sess_9b5irh24v059o24c814tf3jol4
  -rw-------  1 app1 www-data     0 Apr 20 10:43 sess_velp2nf8jcst5dhe358bciq8b6
  </code></pre>
  
  <p>When the user logs into "app1" PHP creates a session with "app1" as owner. But when I try to login to "app2" it sees that there is a session already and tries to open it. Now obviously this won't work because "app2" has no permission to read or write to the session of "app1".</p>
  
  <p>The only strange thing here is that this only happens on macbooks. When I try to login to both applications on my linux machine it simply opens another session with user "app2".</p>
  
  <p>I am running php5 with nginx and php-fpm. I use php sockets in order to connect nginx to php. Both applications have their own socket and run under a different user "app1" and "app2". Therefore the owner of the session depends on the application on which you login.</p>
  
  <p>Does anyone know why php tries to use the same session for macbooks but creates a new session for windows and linux machines? And how would I go about solving this problem?</p>
  
  <p><strong>Edit:</strong>
  A possible solution would be to make www-data owner of the session files but I'd rather have a dedicated user to be owner of these files. So a solution would be appreciated. If there is no solution for the problem I'll have to go with the www-data owner.</p>