error "/var/www/siremis-4.0.0/siremis/log/ERR.log" cannot be opened with mode "a"
Seems that the user that runs the webserver cannot write on that directory. I recall that back in the day when I tested siremis I had to take a look over some script that helped me figuring out the directories needed to stay writable.
Just take a look over the webserver logs and figure out.