Json_Decode Returns Json_Error_Syntax But Online Formatter Says the Json Is Ok

json_decode returns JSON_ERROR_SYNTAX in OpenCart

Seems OpenCart (or somthing else) was changing the " (quotes) to ", therby breaking the JSON.

I added the following line befor I decode the JSON, this fixed the issue.

$rules = str_replace('"', '"', $rules);

PHP json_decode() returns NULL with valid JSON?

It could be the encoding of the special characters. You could ask json_last_error() to get definite information.

Update: The issue is solved, look at the "Solution" paragraph in the question.

Detect bad json data in PHP json_decode()?

Here are a couple of things about json_decode :

• it returns the data, or null when there is an error
• it can also return null when there is no error : when the JSON string contains null
• it raises a warning where there is a warning -- warning that you want to make disappear.

To solve the warning problem, a solution would be to use the @ operator (I don't often recommend using it, as it makes debuging a lot more harder... But here, there is not much of a choice) :

$_POST = array(
    'bad data'
);
$data = @json_decode($_POST);

You'd then have to test if $data is null -- and, to avoid the case in which json_decode returns null for null in the JSON string, you could check json_last_error, which (quoting) :

Returns the last error (if any)
occurred by last JSON parsing.

Which means you'd have to use some code like the following :

if ($data === null
    && json_last_error() !== JSON_ERROR_NONE) {
    echo "incorrect data";
}

json_decode returns NULL after webservice call

EDIT:
Just did some quick inspection of the string provided by the OP. The small "character" in front of the curly brace is a UTF-8 B(yte) O(rder) M(ark) 0xEF 0xBB 0xBF. I don't know why this byte sequence is displayed as  here.

Essentially the system you aquire the data from sends it encoded in UTF-8 with a BOM preceding the data. You should remove the first three bytes from the string before you throw it into json_decode() (a substr($string, 3) will do).

string(62) "{"action":"set","user":"123123123123","status":"OK"}"
            ^
            |
            This is the UTF-8 BOM

As Kuroki Kaze discovered, this character surely is the reason why json_decode fails. The string in its given form is not correctly a JSON formated structure (see RFC 4627)

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