nginx reverse proxy: while reading response header from upstream

2019/01/23 00:20:03 [error] 8492#0: *155 FastCGI sent in stderr: "PHP message: PHP Notice:  Undefined offset: 7 in /usr/share/nginx/domain/domain.ru/www/folder/captcha/kcaptcha.php on line 85
PHP message: PHP Notice:  Undefined offset: 4 in /usr/share/nginx/domain/domain.ru/www/folder/captcha/kcaptcha.php on line 85
PHP message: PHP Notice:  Undefined offset: 6 in /usr/share/nginx/domain/domain.ru/www/folder/captcha/kcaptcha.php on line 85
PHP message: PHP Notice:  Undefined offset: 6 in /usr/share/nginx/domain/domain.ru/www/folder/captcha/kcaptcha.php on line 85" while reading response header from upstream, client: clientip, server: domain.ru, request: "GET /folder/captcha/?PHPSESSID=f5ahqedddlrc7m2oiftql7g21o&tt=0.199709 HTTP/1.1", upstream: "fastcgi://unix:/var/run/php-fpm/php-fpm.sock:", host: "domain.ru", referrer: "https://domain.ru/folder/register.php"

server {
	server_name domain.ru www.domain.ru; 
	charset UTF-8;
	index index.php index.html index.htm;
	listen 443 ssl http2;
	listen [::]:443 ssl http2;
	include "/etc/nginx/server_context.conf";
	location /assets {
		root /usr/share/nginx/static/mltworld;
		#expires max;
	}	
	location / {
		proxy_buffer_size          128k;
		proxy_buffers              4 256k;
		proxy_busy_buffers_size    256k;
		proxy_http_version 1.1;
		proxy_pass  http://2.2.2.2:80/;
		
		proxy_set_header   Host             $host;
		proxy_set_header   X-Real-IP        $remote_addr;
		proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
		proxy_set_header   CF-Connecting-IP $remote_addr;
		
	}
	#####SSL#####
 	ssl_certificate "/etc/pki/nginx/cert/www.domain.ru.crt";
 	ssl_certificate_key "/etc/pki/nginx/private/www.domain.ru.key";
 	ssl_trusted_certificate "/etc/pki/nginx/pem/www.domain.ru.pem";
 	
	include "/etc/pki/nginx/ssl-stapling.conf";
 	#####SSL#####
}

	open_file_cache          max=1000 inactive=20s;
	open_file_cache_valid    30s;
	open_file_cache_min_uses 2;
	open_file_cache_errors   on;

	#ngx_http_headers_module
	add_header X-UA-Compatible "IE=Edge";
	#Запрет на открытие в iframe
	add_header X-Frame-Options SAMEORIGIN;
	
	###ngx_http_core_module
	client_max_body_size       10m;
	client_body_buffer_size    16k;
	client_header_buffer_size 2k;
	large_client_header_buffers 4 8k;
	client_body_timeout 60;
	client_header_timeout 60;
	send_timeout 60;
	
	###ngx_http_proxy_module
	proxy_connect_timeout      60;
	proxy_send_timeout         60;
	proxy_read_timeout         60;
	
	proxy_buffer_size          8k;
	proxy_buffers              8 8k;
	
	#proxy_busy_buffers_size    64k; #proxy_buffer_size + proxy_buffers = proxy_busy_buffers_size
	#proxy_temp_file_write_size 64k; #proxy_buffer_size + proxy_buffers = proxy_temp_file_write_size
	
	#На proxy не нужна комперссия, тк статик файлы уже сжаты, а другие сжимаются на основном сервере
	#include /etc/nginx/gzip-compression.conf;

#WWW redirection NO WWW
server {
	server_name www.domain.ru;
	listen 80;
	listen [::]:80;

    return 301 http://domain.ru$request_uri;
}

server {
	server_name domain.ru www.domain.ru; 
	charset UTF-8;
	index index.php index.html index.htm;
	disable_symlinks if_not_owner from=$root_path;
	access_log /usr/share/nginx/domain/domain.ru/logs/domain.ru.access.log;
	error_log /usr/share/nginx/domain/domain.ru/logs/domain.ru.error.log;
	set $root_path /usr/share/nginx/domain/domain.ru/www;
	root $root_path;
	listen 80;
	listen [::]:80;
	include "/etc/nginx/server_context.conf";
	include "/etc/nginx/location_context.conf";
	location / {
		try_files $uri $uri/ =404;
		sla_pass main;
		
	location / {
		try_files $uri $uri/ /index.php?$uri&$args;
		}	
	}
	
	include /etc/nginx/php-fpm/default/php-fpm.conf;
}

	location ~ \.php$ {
		try_files $uri =404;
		
		fastcgi_index index.php;
		include fastcgi_params;
		fastcgi_param SCRIPT_FILENAME $request_filename;
		fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
		fastcgi_ignore_client_abort off;
		
		
		#Закрывать ли соединение, если клиент не дождался ответа
		#####TEST
		fastcgi_split_path_info ^((?U).+\.ph(?:p\d*|tml))(/?.+)$;
		fastcgi_param PATH_INFO $fastcgi_script_name;

		fastcgi_connect_timeout 150;
		fastcgi_send_timeout 150;
		fastcgi_read_timeout 150;
		fastcgi_buffer_size 128k;
		fastcgi_buffers 4 256k;
		fastcgi_busy_buffers_size 256k;
		fastcgi_temp_file_write_size 256k;
		fastcgi_intercept_errors on;
	}