Issue 502 bad gateway

[iGraphics]

Hello, I got a new dedicated server with Plesk. And I face a problem:

1- When I add a new site and when I click OK to adding a new site when this page loading for make this process other sites get 502 bad gateway!

2- When I change the PHP version for 1 site and when I click OK the other sites get 502 bad geteway

Why?

Please help

 

[IgorG]

Why?

I think this KB article may help with answer - [HUB] 502 Bad Gateway

 

[iGraphics]

Thanks for fast reply ...
I can't find something like my problem I get the error only for 2 seconds when I refresh the site it's work fine.

 

[Bitpalast]

Please follow this article and change your Apache to graceful restarts:
How to enable/disable graceful restart for Apache?