Nginx Fast-CGI 403 error: directory index is forbidden

If you are receiving a 403 error with the message "directory index is forbidden" when trying to access a PHP script via FastCGI in Nginx, it may be caused by incorrect file or directory permissions, incorrect FastCGI configuration, or a missing index file.

Here are some steps you can take to troubleshoot this issue:

1. Check file and directory permissions: Ensure that the file and directory permissions for your PHP scripts are set correctly. The Nginx user (usually "www-data" or "nginx") needs to have read and execute permissions on the PHP script and any directories it is in. You can set the permissions using the chmod command, for example:

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chmod 755 /path/to/php/script.php

1. Check FastCGI configuration: Ensure that the FastCGI configuration in your Nginx server block is correct. Make sure that the fastcgi_pass directive points to the correct FastCGI socket or IP address and port, and that the fastcgi_param directives are set correctly. You may also need to set the SCRIPT_FILENAME parameter to the full path of your PHP script, for example:

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fastcgi_pass unix:/var/run/php/php7.4-fpm.sock;

fastcgi_param SCRIPT_FILENAME /path/to/php/script.php;

1. Check for missing index file: Ensure that an index file (such as index.php) exists in the directory you are trying to access, and that it is set as the default index file in your Nginx configuration. You can set the default index file using the index directive, for example:

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index index.php index.html;

1. Check Nginx error log: Check the Nginx error log for any relevant error messages that may provide further clues to the issue. The error log is usually located in the /var/log/nginx directory.

By following these steps, you should be able to resolve the 403 error with the "directory index is forbidden" message when accessing a PHP script via FastCGI in Nginx.