Fixing WordPress Admin Theme Display and Switching Issues in LNMP Environments

Problem Description

When installing WordPress 3.8 or later in an LNMP environment, the "Appearance" → "Themes" page in the admin dashboard may only show one theme and prevent switching or adding new themes.

Root Cause

This issue is typically caused by the scandir() function being disabled in the PHP configuration. WordPress relies on scandir() to scan the themes directory and list available themes. When this function is disabled, WordPress cannot detect or display the theme list properly.

Solution

Modify the PHP configuration file (php.ini) to remove scandir() from the disabled functions list, then restart the PHP service.

Step 1: Connect to Your Server

Use an SSH client (e.g., PuTTY, Terminal) to connect to your VPS or server.

Step 2: Edit the PHP Configuration File

Open the PHP configuration file with a text editor like vi or nano. Common paths include:

vi /usr/local/php/etc/php.ini

Other possible paths:

• /etc/php.ini
• /etc/php/7.x/fpm/php.ini (for PHP 7.x)
• /usr/local/php7/etc/php.ini

Step 3: Locate the Disabled Functions List

In vi command mode, search for the disable_functions directive:

/disable_functions

You will find a line similar to:

disable_functions = scandir,passthru,exec,system,chroot,chgrp,chown,shell_exec,proc_open,proc_get_status,ini_alter,ini_restore,dl,openlog,syslog,readlink,symlink,popepassthru,stream_socket_server

Step 4: Remove the scandir Function

1. Move the cursor to that line.
2. Press i to enter insert mode.
3. Delete scandir, (including the comma). Ensure the list remains correctly formatted without extra commas.
4. Press Esc to exit insert mode.

Step 5: Save and Exit

In command mode, save the file and exit vi:

:wq

Step 6: Restart the PHP Service

Restart the service based on your LNMP setup:

• For PHP-FPM:

  /etc/init.d/php-fpm restart

  or

  systemctl restart php-fpm

• For Apache:

  /etc/init.d/httpd restart

  or

  systemctl restart apache2

• For Nginx + PHP-FPM: Usually, restarting PHP-FPM is sufficient.

Step 7: Verify the Result

After restarting, refresh the WordPress admin "Appearance" → "Themes" page. All themes should now display correctly, and you should be able to switch or add themes.

Notes and Additional Information

• Configuration File Path: If the above paths are incorrect, find your php.ini location with:

  php --ini | grep 'Loaded Configuration File'

• Security Consideration: The scandir() function is relatively low-risk, but the disabled functions list is often set for security. Consult your server administrator if you are on shared hosting or have strict security requirements.
• WordPress Version: This solution applies to WordPress 3.8 and later, including modern versions (5.x, 6.x).
• Alternative: If you cannot modify php.ini (e.g., on shared hosting), try overriding the setting in your site's .htaccess file (Apache) or Nginx configuration (if allowed):

  php_value disable_functions ""

  Or, more precisely, remove only scandir:

  php_admin_value disable_functions "passthru,exec,system,..." # List all other functions except scandir

After completing these steps, WordPress theme management should function normally.