PHP XML UTF-8 with special characters throws errors

Question

I am having some issues receiving UTF-8 XML files back from DHL API. As long as I don't send it's way any special characters like ś or ó, everything works just fine, but with these characters my app crashes when trying to load XML file received from DHL throwing me errors:

Warning:  DOMDocument::loadXML() [domdocument.loadxml]: 
Opening and ending tag mismatch: AddressLine line 43 and Consignee 
in Entity, line: 53 in D:\xampp\htdocs\ebay\catch2.php on line 29

Warning:  DOMDocument::loadXML() [domdocument.loadxml]: 
Opening and ending tag mismatch: Consignee line 40 and res:ShipmentValidateResponse 
in Entity, line: 97 in D:\xampp\htdocs\ebay\catch2.php on line 29

Warning:  DOMDocument::loadXML() [domdocument.loadxml]: Premature end of 
data in tag ShipmentValidateResponse line 1 in Entity, line: 98
in D:\xampp\htdocs\ebay\catch2.php on line 29

This is a XML I send

<?xml version="1.0" encoding="utf-8"?>
... 
<AddressLine>address</AddressLine> 
<AddressLine>asfśó</AddressLine> 
...

What I receive:

<?xml version="1.0" encoding="UTF-8"?>
...
Lines 40 to 43:

<Consignee>
<CompanyName>Person</CompanyName>
<AddressLine>address</AddressLine>
<AddressLine>asf??ddressLine>
...

Here is what happens around line 29:

$responseXml = $session->sendHttpRequest($requestXmlBody);
if(stristr($responseXml, 'HTTP 404') || $responseXml == '')
    die('<P>Error sending request');
$responseXml = utf8_decode($responseXml);
$responseDoc = new DOMDocument('1.0', 'UTF-8');
$responseDoc->loadXML($responseXml);

E: Removing utf8_decode doesn't help much. Just a new error:

Warning:  DOMDocument::loadXML() [domdocument.loadxml]: 
Input is not proper UTF-8, indicate encoding !
Bytes: 0xF3 0x3C 0x2F 0x41 in Entity, line: 43 in D:\xampp\htdocs\ebay\catch2.php on line 29

E2: hex dump

0000-0010:  3c 3f 78 6d-6c 20 76 65-72 73 69 6f-6e 3d 22 31  <?xml.ve rsion="1
0000-0020:  2e 30 22 20-65 6e 63 6f-64 69 6e 67-3d 22 55 54  .0".enco ding="UT
0000-0030:  46 2d 38 22-3f 3e 3c 72-65 73 3a 53-68 69 70 6d  F-8"?><r es:Shipm

line 43:

0000-0960:  4c 69 6e 65-3e 0a 20 20-20 20 20 20-20 20 3c 41  Line>... ......<A
0000-0970:  64 64 72 65-73 73 4c 69-6e 65 3e 61-73 66 3f f3  ddressLi ne>asf?.
0000-0980:  3c 2f 41 64-64 72 65 73-73 4c 69 6e-65 3e 0a 20  </Addres sLine>..

Answer 1

Don't use utf8_decode !

That's what's screwing up your encoding.
utf8_decode converts UTF-8 encoded text to Latin1 encoded text. That's not what you want or need. Just parse the XML as is without encoding conversion.