nginx反代cloudflare出现502错误问题

proxy_ssl_name $host;  
proxy_ssl_server_name on;

location / {  
        proxy_pass https://域名;  
        #Proxy Settings  
        proxy_redirect off;  
        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_ssl_name $host;  
        proxy_ssl_server_name on;  
        proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;  
        # proxy_max_temp_file_size 0;  
        proxy_connect_timeout 90;  
        proxy_send_timeout  90;  
        proxy_read_timeout 90;  
        proxy_buffer_size 64k;  
        proxy_buffers  32 32k;  
        proxy_busy_buffers_size 128k;  
        proxy_temp_file_write_size 64k;  
}