OK So after reboot it tried to generate again and now server hangs… below is the system crtl status of apache2
pi@raspberrypi:~ $ sudo systemctl status apache2
* apache2.service - The Apache HTTP Server
   Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-09-19 21:14:48 ACST; 3min 37s ago
  Process: 1530 ExecStop=/usr/sbin/apachectl stop (code=exited, status=0/SUCCESS)
  Process: 1537 ExecStart=/usr/sbin/apachectl start (code=exited, status=0/SUCCESS)
 Main PID: 1541 (apache2)
   CGroup: /system.slice/apache2.service
           |-1541 /usr/sbin/apache2 -k start
           |-1545 /usr/sbin/apache2 -k start
           |-1546 /usr/sbin/apache2 -k start
           |-1547 /usr/sbin/apache2 -k start
           |-1548 /usr/sbin/apache2 -k start
           |-1549 /usr/sbin/apache2 -k start
           |-1550 /usr/sbin/apache2 -k start
           |-1560 /bin/bash /var/www/html/scripts/odt2pdf/odt2pdf.sh /var/www/html/documents/facture/FA1809-0001/FA1809-0001_Cover jodconverter
           |-1562 /usr/lib/libreoffice/program/oosplash --invisible --accept=socket,host=127.0.0.1,port=8100;urp; --nofirststartwizard --headless -env:UserInstallation=file:////tmp/
           |-1617 /usr/lib/libreoffice/program/soffice.bin -env:UserInstallation=file:////tmp/ --invisible --accept=socket,host=127.0.0.1,port=8100;urp; --nofirststartwizard --headless
           `-1658 /usr/sbin/apache2 -k start
Sep 19 21:14:48 raspberrypi systemd[1]: Starting The Apache HTTP Server...
Sep 19 21:14:48 raspberrypi apachectl[1537]: AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
Sep 19 21:14:48 raspberrypi systemd[1]: Started The Apache HTTP Server.apache has to be reset to stop it from hanging




