- var_export: documentation ( source)
- json_encode: documentation ( source)
<?php
$e = new Exception();
// This line cause problem :(
// Comment it to see the difference.
// (string) $e;
// This line show the clue (PHP Warning: ...).
var_export($e);
// This line will be affected.
var_export(json_encode([$e]));
// But This line still OK.
var_export(json_encode($e));