Steps to reproduce:

1. Open template -> Discovery list -> Graph prototypes -> Preview

Error

```
**
2022/02/16 15:24:08 [error] 26534#26534: *37 FastCGI sent in stderr: "PHP message: PHP Notice: Undefined offset: 320677 in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2013
PHP message: PHP Notice: Undefined offset: 320677 in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2013
PHP message: PHP Notice: Undefined offset: 320677 in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2013
PHP message: PHP Notice: Undefined offset: 320677 in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2013
PHP message: PHP Notice: Undefined offset: 320677 in /usr/share/zabbix/include/classes/graphdraw/CLineGraphDraw.php on line 2013" while reading response header from upstream, client: 10.13.8.10, server: d01toolszbweb1t, request: "GET /chart3.php?sid=a5c52472243a6f76&period=3600&name=PostgreSQL%3A%20%7B%23EXTNAME%7D&width=900&height=200&graphtype=0&legend=1&percent_left=0&percent_right=0&ymin_type=1&ymax_type=0&yaxismin=0&yaxismax=100&ymin_itemid=0&ymax_itemid=0&showworkperiod=0&showtriggers=0&i%5B0%5D=gi%3A1075982%2Cit%3A312245%2Cso%3A0%2Cfl%3A2%2Cty%3A0%2Cdr%3A0%2Cya%3A0%2Cca%3A2%2Cca%3A2%2Cdr%3A0%2Cdr%3A0%2Cya%3A0%2Cya%3A0%2Cco%3A0000CC&i%5B1%5D=gi%3A1075983%2Cit%3A312237%2Cso%3A1%2Cfl%3A2%2Cty%3A0%2Cdr%3A0%2Cya%3A0%2Cca%3A2%2Cca%3A2%2Cdr%3A0%2Cdr%3A0%2Cya%3A0%2Cya%3A0%2Cco%3A00CC00&i%5B2%5D=gi%3A1075984%2Cit%3A312257%2Cso%3A2%2Cfl%3A2%2Cty%3A0%2Cdr%3A0%2Cya%3A0%2Cca%3A2%2Cca%3A2%2Cdr%3A0%2Cdr%3A0%2Cya%3A0%2Cya%3A0%2Cco%3AFFFFFF&i%5B3%5D=gi%3A1075985%2Cit%3A312253%2Cso%3A3%2Cfl%3A2%2Cty%3A0%2Cdr%3A0%2Cya%3A0%2Cca%3A2%2Cca%3A2%2Cdr%3A0%2Cdr%3A0%2Cya%3A0%2Cya%3A0%2Cco%3ACC0000&i%5B4%5D=gi%3A1075986%2Cit%3A312249%2Cso%3A4%2Cfl%3A2%2Cty%3A0%2Cdr%3A0%2Cya%3A0%2Cca%3A2%2Cca%3A2%2Cdr%3A0%2Cdr%3A0%2Cya%3A0%2Cya%3A0%2Cco%3ACCCC00 HTTP/1.0", upstream: "fastcgi://unix:/var/opt/rh/rh-php72/run/php-fpm/zabbix.sock:", host: "zabbix.ru", referrer: "https://zabbix.ru/graphs.php?form=update&parent_discoveryid```
 

How to fix this error ?