You have upgraded from Debian 7 to Debian 8 and you are usign syslog-ng.

You will be in a little bit in trouble with syslog-ng

You can check this with systemctl status syslog-ng.service

syslog-ng.service start request repeated too quickly, refusing to start

syslog-ng service is not starting.

Check your local config file search after ” unix-stream(“/dev/log”);”

People with custom syslog-ng configurations will most likely face upgrade problems due to the unix socket type mismatch between systemd and syslog-ng old configuration file:

• systemd creates /dev/log as unix-dgram
• syslog-ng < 3.2.5 expected /dev/log to be unix-stream (configuration file)

If you use ‘unix-stream (“/dev/log”)’ in one of your log messages sources, you will need to manually change it to ‘unix-dgram (“/dev/log”)’.

Found here

https://unix.stackexchange.com/questions/202044/syslog-ng-service-not-starting-with-systemd-but-command-works-fine