Applicable to:
- Plesk for Linux
Symptoms
-
Website or website preview is unavailable:
PLESK_INFO: 502 Bad Gateway
-
In the log files
/var/log/nginx/error.logor/var/www/vhosts/example.com/logs/proxy_error_log, the following error messages can be found:CONFIG_TEXT: [error] 14790#0: *188 upstream sent too big header while reading response header from upstream, client: 203.0.113.2, server: subdomain.example.com, request: "POST /admin_catalog.php HTTP/1.1", upstream: "http://10.0.0.1:7080/admin_catalog.php", host: "subdomain.example.com", referrer: "http://subdomain.example.com/admin_catalog.php"
CONFIG_TEXT: [error] 707#0: *2016153 FastCGI sent in stderr: "PHP message: Error checking in buffer: The buffer you checked in was not checked out" while reading upstream, client: 203.0.113.2, server: example.com, request: "POST /wp-admin/admin-ajax.php HTTP/1.1", upstream: "fastcgi://unix:///var/www/vhosts/system/example.com/php-fpm.sock:", host:"example.com", referrer: "https://example.com/wp-admin/post-new.php?wp-post-new-reload=true"
CONFIG_TEXT: 2020/04/27 20:07:05 [error] 4966#0: *39052 proxy_buffer_size x is not enough for cache key, it should be increased to at least xx, client: *****, server: example.com, request: "GET /wp-admin/admin-post.php.."
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The same symptoms can be observed when WHMCS is installed on the same server as Plesk and when navigating to WHMCS > Clientes > John Doe > Invoices.
Cause
A request cannot be processed by the proxy server because of insufficient buffer size.
Resolution
-
Go to Domains > example.com > PHP Settings and check the selected PHP handler (the field run PHP as).
-
Go to Domains > example.com > Apache & nginx Settings, scroll down to the field Additional nginx directives and set the following parameters in accordance with the used PHP handler:
-
For PHP handler FPM application served by Nginx and disabled Proxy Mode:
CONFIG_TEXT: fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k; -
For other cases:
CONFIG_TEXT: proxy_buffers 8 16k;
proxy_buffer_size 32k;
-
Increase values of these parameters if it is needed.
-
Connect to the server using SSH.
-
Open the file
/etc/nginx/nginx.conffor editing. -
Increase the following parameters in the section
http {:CONFIG_TEXT: proxy_buffers 8 16k;
proxy_buffer_size 32k;
fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k; -
Restart nginx to apply changes:
# service nginx restart
Increase values of these parameters if it is needed.
Comments
13 comments
nice 2 know :-)
Doesn't work. How do you calculate the buffer size?
Hello @Sharul,
For determining the size which will be suitable for you, please, refer to these links:
https://gist.github.com/magnetikonline/11312172#determine-fastcgi-response-sizes
http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#fastcgi_buffer_size
Not working for me
Hello Khoneketa,
Error 502 for websites may have a variety of causes, e.g. issues with PHP or Apache down.
Try checking this article for guidance: https://support.plesk.com/hc/en-us/articles/115001463089--HUB-502-Bad-Gateway
In case this wouldn't help, consider submitting a request for Plesk Support:
https://support.plesk.com/hc/en-us/articles/213608509-How-to-submit-a-request-to-Plesk-support-
Works for me as well :)
Thanks very much !! Work fine ;-)
Hello,
In my logs I only have this:
upstream sent unexpected FastCGI record: 3 while reading response header from upstream
All websites on the server are unreachable and give Error 502
I contacted support and got just this as a solution. I applied it. But the situation repeats.
Hello @Kea,
This issue was addressed in ticket already. If you are working with support directly, feel free to re-open the ticket as issue may have different symptoms and have another cause.
Nothing ... I've really tried them all but I always get a 502 error. I visualize the site (Magento 2) with "website preview".
In the log file "/var/log/sw-cp-server/error_log" I read the error: "upstream sent too big header while reading response header from upstream, client: 127.0.0.1".
I have modified both from "Apache & nginx Settings> Additional nginx directives" and directly from "/etc/nginx/nginx.conf" but nothing.
What else can I do? Anyone have other indications?
Verificato il mio file php.ini che viene fornito con Applicazione FPM servita da nginx, Inserisco il codice
fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k;
ma ricevo il messaggio di errore
"Configurazione Apache non valida: AH00526: errore di sintassi sulla riga 1 di /var/www/vhosts/system/partyinfesta.shop/conf/vhost.conf: comando 'fastcgi_buffering' non valido, forse errato o definito da un modulo non incluso nella configurazione del server"
Ho comunque provato tutte le configurazioni ma ottengo sempre lo stesso messaggio di errore
It works for me, thanks.
Article Improvement for "For all domains"
Increase values of these parameters if it is needed.
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