FCGI: attempt to connect to Unix domain socket /var/run/php5.6-fpm.sock (*) failed

Bonjour,
J’ai installé php5.6-fpm en plus de php7.3-fpm sur Debian Buster d’après ce tuto Stretch
https://tecadmin.net/install-multiple-php-version-with-apache-on-debian/
(pas d’équivalent Buster encore, à ma connaissance).

Voici les éléments principaux de ma conf:

root@kmcs:/etc/php# cat /etc/php/5.6/fpm/pool.d/www.conf 
[www]
user = kmc
group = www-data
listen = /run/php/php5.6-fpm.sock
listen.owner = kmc
listen.group = www-data
pm = dynamic
pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3
env[UMASK] = 0002

root@kmcs:/etc/php# cat /etc/apache2/sites-enabled/lef-prod.conf 
<VirtualHost *:80>
        ServerAdmin     kmc@localhost
        ServerName      lef-prod.loc
        ServerAlias     www.lef-prod.loc

        DocumentRoot /var/www/lef-prod

        # Possible values include: debug, info, notice, warn, error, crit, alert, emerg.
        LogLevel warn
        ErrorLog /var/log/apache2/error.log
        CustomLog /var/log/apache2/access.log common

        <Directory /usr/lib/cgi-bin>
                Require all granted
        </Directory>

       <FilesMatch \.php$>
                #SetHandler "proxy:unix:/var/run/php/php7.3-fpm.sock|fcgi://localhost/"
                SetHandler "proxy:unix:/var/run/php5.6-fpm.sock|fcgi://localhost/"
       </FilesMatch>
</virtualhost>

root@kmcs:/etc/php# systemctl restart php5.6-fpm
root@kmcs:/etc/php# systemctl status php5.6-fpm
● php5.6-fpm.service - The PHP 5.6 FastCGI Process Manager
   Loaded: loaded (/lib/systemd/system/php5.6-fpm.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2019-10-14 15:55:01 CEST; 7s ago
 Docs: man:php-fpm5.6(8)
 Main PID: 20129 (php-fpm5.6)
   Status: "Ready to handle connections"
Tasks: 3 (limit: 4915)
   Memory: 10.9M
   CGroup: /system.slice/php5.6-fpm.service
       ├─20129 php-fpm: master process (/etc/php/5.6/fpm/php-fpm.conf)
       ├─20130 php-fpm: pool www
       └─20131 php-fpm: pool www

oct. 14 15:55:01 kmcs systemd[1]: Starting The PHP 5.6 FastCGI Process Manager...
oct. 14 15:55:01 kmcs systemd[1]: Started The PHP 5.6 FastCGI Process Manager.

# ll /var/www/lef-prod/inf.php 
-rw-r--r-- 1 kmc www-data 24 oct.  14 12:15 /var/www/lef-prod/inf.php

Mais lorsque j’essaie d’atteindre une page :

# cat /var/log/apache2/error.log
[Mon Oct 14 16:18:08.071754 2019] [proxy:error] [pid 20444] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /var/run/php5.6-fpm.sock (*) failed
[Mon Oct 14 16:18:08.071820 2019] [proxy_fcgi:error] [pid 20444] [client 127.0.0.1:41920] AH01079: failed to make connection to backend: httpd-UDS

Le problem venait de l’ancien fichier de conf qui cherchait le fichier ailleurs que dans la nouvelle conf Buster qui a déplacé le socket dans
/var/run**/php**/php5.6-fpm.sock