Thanks for creating this. After having pi-hole running for days/weeks I get the following error logs when trying to load the pi-hole gui:
2016/09/23 14:57:19 [error] 242#242: *49 FastCGI sent in stderr: "PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 93 bytes) in /var/www/html/admin/data.php on line 176" while reading response header from upstream, client: 192.168.1.131, server: , request: "GET /admin/api.php?summaryRaw&getQuerySources HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.252", referrer: "http://192.168.1.252/admin/"
2016/09/23 14:57:19 [error] 242#242: *44 FastCGI sent in stderr: "PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 96 bytes) in /var/www/html/admin/data.php on line 176" while reading response header from upstream, client: 192.168.1.131, server: , request: "GET /admin/api.php?summary HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.252", referrer: "http://192.168.1.252/admin/"
2016/09/23 14:57:19 [error] 242#242: *50 FastCGI sent in stderr: "PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 96 bytes) in /var/www/html/admin/data.php on line 176" while reading response header from upstream, client: 192.168.1.131, server: , request: "GET /admin/api.php?getForwardDestinations HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.252", referrer: "http://192.168.1.252/admin/"
2016/09/23 14:57:19 [error] 242#242: *47 FastCGI sent in stderr: "PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 96 bytes) in /var/www/html/admin/data.php on line 176" while reading response header from upstream, client: 192.168.1.131, server: , request: "GET /admin/api.php?overTimeData HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.252", referrer: "http://192.168.1.252/admin/"
2016/09/23 14:57:19 [error] 242#242: *48 FastCGI sent in stderr: "PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 96 bytes) in /var/www/html/admin/data.php on line 176" while reading response header from upstream, client: 192.168.1.131, server: , request: "GET /admin/api.php?getQueryTypes HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "192.168.1.252", referrer: "http://192.168.1.252/admin/"
These are the requests to the backend for the graph content, and the end result is that the graphs never load (you're left with spinning 'loading arrows').
It's discussed in the following github page, and you may need to upgrade php-fpm version:
https://github.com/pi-hole/pi-hole/issues/375
I'm available to test anything you need to. I'll also try to fix it myself if/when I have the time.