Trend Graph not working
 

I recently migrated my old HL stats that were working on php5 to php7 using the hlstats provided here https://github.com/nikooo777/hlstatsx-community-edition
now there are Two problems I am facing:-

1) Server load graph is coming broken
2) The player trend graph is giving error as attached in image below

For further details I am using Ubuntu Version 16.04 previously was using 14.04 as I am changing my hosting and it does not support ubuntu 14.04 I have to use Ubuntu 16.04. Also I don't want to use Nomiscz Hlstats as when I try to upload my old database into it the database is uploaded correctly but the data does not show properly.

Please help me out.