Hi everyone
I faced the same issue.
I was digging into the code a little bit and this issue is caused by PHP 7.1 and the changed behavior of type conversion and the unavailability of the empty bracket operator.
Note: As of PHP 7.1.0, applying the empty index operator on a string throws a fatal error. Formerly, the string was silently converted to an array.
(taken from http://php.net/manual/en/language.types.array.php)
Actually, a code change needs to be implemented, which is replacing [] with corresponding array_push calls (ref. http://php.net/manual/de/function.array-push.php).
I have tested the implementation in libs\pChart\class\pData.class.php and it helped to fix the error message, but charts haven’t been displayed yet (assuming that other components are involved as well).
#example modification in pData.class.php:
###in construct:
$this->Data = array();
####replace empty bracket operator by array_push:
$this->Data["Series"][$SerieName]["Data"][] = $Value;
array_push($this->Data["Series"][$SerieName]["Data"], $Value);