Call to undefined function __() error - phpMyAdmin with LNMP

Question

I have a problem with phpMyAdmin. When I accessed the page, it gave a white blank page.

Here is the error log

2016/07/26 11:20:16 [error] 2591#2591: *2 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function __() in /usr/share/phpmyadmin/libraries/core.lib.php:235
Stack trace:
#0 /usr/share/phpmyadmin/libraries/core.lib.php(308): PMA_fatalError('The [a@./url.ph...')
#1 /usr/share/phpmyadmin/libraries/common.inc.php(90): PMA_warnMissingExtension('mbstring', true)
#2 /usr/share/phpmyadmin/index.php(12): require_once('/usr/share/phpm...')
#3 {main}
  thrown in /usr/share/phpmyadmin/libraries/core.lib.php on line 235" while reading response header from upstream, client: XX.XX.XX.XX, server: localhost, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock:", host: "XX.XX.XX.XX:8080"

I followed this answer (https://stackoverflow.com/a/21321260) by changing the owner of /var/lib/php/sessions to www-data and made that directory writable.

But it can't help, the problem persists.

My LNMP is:

1. Debian 8 (Jessie) 64 bit
2. PHP7 (PHP-FPM)
3. MariaDB 10.0
4. Nginx

This is my nginx server block:

server {
    listen 8080;
    server_name localhost;
    root /usr/share/phpmyadmin;
    index index.php index.html index.htm;

    access_log /var/log/nginx/phpmyadmin.com.access.log;
    error_log /var/log/nginx/phpmyadmin.com.error.log;

    if (!-e $request_filename) {
        rewrite ^/(.+)$ /index.php?url=$1 last;
        break;
    }
    location ~ .php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }
}   

What am I supposed to do?

Answer 1

From your log message, it seems that the mbstring extension is missing:

/usr/share/phpmyadmin/libraries/common.inc.php(90): PMA_warnMissingExtension('mbstring', true)

Since you are using Debian, please use this to install the extension:

sudo apt-get install php7.0-mbstring