What does the FastCGI sent in stderr: error mean?

Question

Nginx

I'll admit right away - I'm a newbie. In the logs, I found a frequently repeated error FastCGI sent in stderr:
what does it mean?

Answer 1

"FastCGI sent in stderr" is not an error. Error further down the line. And this is just an inscription that a script running under fastcgi spit out an error