[error] 5378#5378: *2481 FastCGI sent in stderr: “PHP message: PHP Warning: session_start(): open(/var/lib/php/session/sess_11d6edde5218ffa04f1fc6f231efe25d, O_RDWR) failed: No such file or directory (2) in /code/wordpress/wp-content/themes/argon-theme-1.3.5/functions.php on line 432

需要从两个方面入手，一个是wordpress本身，也就是它的php配置文件，另一个是修改nginx虚拟主机的限制。