Variable not replaced - AH01079: failed to make connection to backend: httpd-UDS

  • Since updating I-MSCP 1.2.11 to 1.2.14 yesterday, websites are not delivered. Instead an error 503 is shown, the log files contain the following entry, showing the PHP5 FPM socket is not set:

    1. [Mon Feb 29 07:48:51.282895 2016] [proxy:error] [pid 28662:tid 140646627120896] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /run/php5-fpm-dmn.tld.sock (*) failed
    2. [Mon Feb 29 07:48:51.282937 2016] [proxy_fcgi:error] [pid 28662:tid 140646627120896] [client] AH01079: failed to make connection to backend: httpd-UDS

    NGINX has no problem with delivering the panel.

    Any suggestions what to do?

  • @Starlight

    Output of the following command ?

    1. # service php5-fpm status


  • Distro, codename ?


  • Debian jessie with upstart ???


  • yes, with upstart.

    I'm not sure where this should lead to. For me, it looks like PHP5 FPM cannot create the socket file in /var/run due to permission problems with the vu-user and therefore cannot connect to this socket. The main problem seems to be AH02454. There is only one PHP5 FPM socket created: for vu2000 (what is the panel). This leads me to the conclusion that Apache or the imscp configuraton create the problem.

  • @Starlight

    There is no socket created with vu2000 user by PHP5-FPM... The panel don't use PHP5-FPM. The socket for the panel is created by a specific script through spawn-fcgi.
    The problem here is your upstart. The PHP5-FPM process is not running in reality ;)

    Can I access your server?


  • As said through our conversation: You should not use Upstart with Debian Jessie. Upstart is not really supported.
    You can always try:

    I'll investigate later about this problem (Jessie + Upstart). It is not my prioriry because normally, you should use systemd.


  • I found the problem: in one of the php5-fpm pool files, the {ALLOW_URL_FOPEN} variable was not replaced by a valid boolean string. Unfortunately, I could not find it in the php5-fpm logs.

    To find it, I tried:

    1. /usr/sbin/php5-fpm -n

    Looks, like it is i-MSCP related. However, it needs a bit more Investigation how it could happen and why only with one vhost.