SOLVED cPanel php-fpm not restarting

When upgrading from 70.0.26 to 70.0.31 I had no issues. But when provisioning a new server at 70.0.31 I am getting the below problem.

## The issue
When I create a new website on a subdomain it works for a few minutes then shows the error:
```
Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Additionally, a 503 Service Unavailable error was encountered while trying to use an ErrorDocument to handle the request.
```

If I tail the `apache2/error_log` and refresh the web page I get this:
```
[Wed May 02 15:29:12.931381 2018] [proxy:error] [pid 23528:tid 140003464619776] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/cpanel/ea-php70/root/usr/var/run/php-fpm/01ec0cf803682d3d54723265378c356d92c1d647.sock (*) failed
[Wed May 02 15:29:12.931430 2018] [proxy_fcgi:error] [pid 23528:tid 140003464619776] [client 120.29.52.39:54765] AH01079: failed to make connection to backend: httpd-UDS
```

Now sometime after around 5-10 minutes it will start working again on its own. (maybe after it restarts php-fpm itself)

## The temporary solution
But if I go into the WHM `PHP-FPM service for Apache` and manually restart the php-fpm service, it will start working straight away.

 

Ok couldn't edit the above because your system says it's spam so ill add it here:

After the WordPress website is created there is a delay of 2 minutes before the .htaccess file is created (inside the public_html). As soon as these are created the website dies with the '503' error.

Even if I try and create it before the apache does it just appends the below and then dies:
```
# php -- BEGIN cPanel-generated handler, do not edit
# NOTE this account's php is controlled via FPM and the vhost, this is a place holder.
# Do not edit. This next line is to support the cPanel php wrapper (php_cli).
# AddType application/x-httpd-ea-php70 .php .phtml
# php -- END cPanel-generated handler, do not edit
```

If I manually restart php-fpm after the website dies it works again, or as said before it will start working itself again after 5-10 minutes (I assume when cPanel restarts php-fpm itself).

As I don't have a clear time when apache will do this I can't confidently restart php-fpm. So the website always have a downtime when provisioned.

 

Seems the issue is happening on servers upgraded from earlier versions as well.