Let's say you have a web server that is configured with PHP and SSL, and you get something like this when attempting to get a PHP page over HTTPS.

Let's say the web servers log has something like this. This suggests some issue with FastCGI.

2021/07/03 04:04:58 [error] 54817#54817: *2 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, client: 10.14.55.2, server: www.example.com, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://unix:/run/php-fpm/www.sock:", host: "www.example.com", referrer: "http://www.example.com/index.php"

Check out my articles:

• Nginx and PHP FastCGI on Docker TCP port 9000
• Nginx and PHP FastCGI on Docker using UNIX socket