Primary script unknown 🐘 PHP

FastCGI sent in stderr: "Primary script unknown"

Nginx passed a script path to PHP-FPM that PHP-FPM couldn’t find — usually a wrong SCRIPT_FILENAME or root.

Seen on: PHP

Meaning

Nginx builds SCRIPT_FILENAME from $document_root$fastcgi_script_name. If root is wrong, the file doesn’t exist, or PHP-FPM runs in a different filesystem (container), FPM answers “Primary script unknown” and the browser shows “File not found.”

Common causes

  • Missing/incorrect fastcgi_param SCRIPT_FILENAME
  • Nginx root differs from where the files are
  • PHP-FPM in a container with a different path
  • open_basedir/chroot restrictions

⚡ Quick fix

  1. Add fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
  2. Make root match the real path in both Nginx and PHP-FPM
  3. Mount the same path in both containers

Detailed fix by platform

Nginx

  1. include fastcgi_params; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

How to diagnose

  1. Path — What SCRIPT_FILENAME does Nginx send?
  2. FPM view — Does that path exist inside FPM?

🧠 Still stuck? Analyze your error

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