symfony条令结果查询格式错误

我有一个奇怪的情况,我不知道如何解决它。

我在Doctrine中得到了一个查询结果,格式看起来很奇怪。

我使用Doctrine执行一个查询,如下例所示:

$query = "select ... from ..."
$stmt = $this->oracleDB->prepare($query); 
(This oracleDB is configured in the config.yml with "charset: ISO-8859-1" and "driver: oci8")
$stmt->bindValue(1, $variable, "...");
more binds...
$stmt->execute();
$results = $stmt->fetchAll();

大多数情况下,结果是正常的,json_encode可以工作,但有时我会得到类似下一个结果的结果:

dump($results);
array:1 [▼
  0 => array:6 [▼
    "BLA1" => "xx"
    "BLA2" => "XX"
    "BLA3" => "XX"
    "BLA4" => "XX"
    "BLA5" => b"XX"
    "BLA6" => "XX"
  ]
]
var_dump($results);
array (size=1)
  0 => 
    array (size=12)
      'BLA1' => string 'XX' (length=2)
      'BLA2' => string 'XX' (length=2)
      'BLA3' => string 'XX' (length=2)
      'BLA4' => string 'XX' (length=2)
      'BLA5' => string 'X�X' (length=3)
      'BLA6' => string 'XX' (length=2)

dump(json_encode($results));
false

如果我取消设置bla5,json_编码工作得很好。

unset($result[0]['BLA5']);

dump($result);
array:1 [▼
0 => array:5 [▼
    "BLA1" => "xx"
    "BLA2" => "XX"
    "BLA3" => "XX"
    "BLA4" => "XX"
    "BLA6" => "XX"
  ]
]

dump(json_encode($results));
"[{"BLA1":"XX","BLA2":"XX","BLA3":"XX","BLA4":"XX","BLA6":"XX"}] ◀"

有什么想法吗?