JSON wrong response [duplicate]

This question already has an answer here:

• PHP: “Notice: Undefined variable” and “Notice: Undefined index” 18 answers

My Problem:

After the execute of this javascript Code:

   $.post( $("#deleteAccountForm").attr("action") ,$("#deleteAccountForm :input").serializeArray(),function(response){
        alert(response);

        if(response.message === "nomatch"){
            $('#hiddenNotFound').show(300).delay(5000).fadeOut();
        }
    }); 

It response this:

<br />
<font size='1'><table class='xdebug-error xe-notice' dir='ltr' border='1' cellspacing='0' cellpadding='1'>
<tr><th align='left' bgcolor='#f57900' colspan="5"><span style='background-color: #cc0000; color: #fce94f; font-size: x-large;'>( ! )</span> Notice: Undefined index: id in myPath\deleteAccountStuff.php on line <i>7</i></th></tr>
<tr><th align='left' bgcolor='#e9b96e' colspan='5'>Call Stack</th></tr>
<tr><th align='center' bgcolor='#eeeeec'>#</th><th align='left' bgcolor='#eeeeec'>Time</th><th align='left' bgcolor='#eeeeec'>Memory</th><th align='left' bgcolor='#eeeeec'>Function</th><th align='left' bgcolor='#eeeeec'>Location</th></tr>
<tr><td bgcolor='#eeeeec' align='center'>1</td><td bgcolor='#eeeeec' align='center'>0.0000</td><td bgcolor='#eeeeec' align='right'>385416</td><td bgcolor='#eeeeec'>{main}(  )</td><td title='myPath\deleteAccountStuff.php' bgcolor='#eeeeec'>...\deleteAccountStuff.php<b>:</b>0</td></tr>
</table></font>
<br />
<font size='1'><table class='xdebug-error xe-notice' dir='ltr' border='1' cellspacing='0' cellpadding='1'>
<tr><th align='left' bgcolor='#f57900' colspan="5"><span style='background-color: #cc0000; color: #fce94f; font-size: x-large;'>( ! )</span> Notice: Undefined index: versuche in myPath\deleteAccountStuff.php on line <i>8</i></th></tr>
<tr><th align='left' bgcolor='#e9b96e' colspan='5'>Call Stack</th></tr>
<tr><th align='center' bgcolor='#eeeeec'>#</th><th align='left' bgcolor='#eeeeec'>Time</th><th align='left' bgcolor='#eeeeec'>Memory</th><th align='left' bgcolor='#eeeeec'>Function</th><th align='left' bgcolor='#eeeeec'>Location</th></tr>
<tr><td bgcolor='#eeeeec' align='center'>1</td><td bgcolor='#eeeeec' align='center'>0.0000</td><td bgcolor='#eeeeec' align='right'>385416</td><td bgcolor='#eeeeec'>{main}(  )</td><td title='myPath\deleteAccountStuff.php' bgcolor='#eeeeec'>...\deleteAccountStuff.php<b>:</b>0</td></tr>
</table></font>
{"message":"nomatch","versuche":"1"}

As you can see, the response is full of HTML stuff and my required JSON-Array on the Last line.

PHP-Code:

            header('Content-type: application/json');
            $arr = array ('message'=>'nomatch','versuche'=>"$versuche");
            echo json_encode($arr);

I tried it also with "die(json_encode(array(...)));" but the result remains the same. The "alert(response)" doesn't appear.

My Question:

Why does the HTML-Stuff appear in my JSON-response? Why does the alert Dialog didn't appear?

Hope this is enough information to get a clue what I could had made wrong.