Hello,
I'm sending a JSON with an XML to server and sometimes I get an error:
{"":{"Value":"","Messages":["Invalid character in the given encoding. Line 21, position 47."]}}

It looks like the message that I'm sending is not in UTF-8 format.

Here is the code (and a strip down XML) that gives me this error:

Code:
Public Sub sendtoserver()
Dim objHTTP As New MSXML2.ServerXMLHTTP60
Dim strJSON As String
Dim Url As String
Dim strUserName As String
Dim strPassword As String
Dim strCompanyId As String
Dim strSoftwareId As String
Dim strXML As String
Dim result As String


strXML = ""
strXML = strXML & "<?xml version='1.0' encoding='utf-8'?>"
strXML = strXML & "<OutgoingInvoicesData xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns='http://fina.hr/eracun/erp/OutgoingInvoicesData/v3.2'>"
strXML = strXML & "  <Header>"
strXML = strXML & "    <SupplierID>435455335</SupplierID>"
strXML = strXML & "    <InvoiceType>1</InvoiceType>"
strXML = strXML & "  </Header>"
strXML = strXML & "  <OutgoingInvoice>"
strXML = strXML & "    <SupplierInvoiceID>1212-1-1</SupplierInvoiceID>"
strXML = strXML & "    <BuyerID>455465456</BuyerID>"
strXML = strXML & "    <InvoiceEnvelope>"
strXML = strXML & "      <Invoice xmlns:cbc='urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2' xmlns:sac='urn:oasis:names:specification:ubl:schema:xsd:SignatureAggregateComponents-2' xmlns:ext='urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2' xmlns:cac='urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2' xmlns:sig='urn:oasis:names:specification:ubl:schema:xsd:CommonSignatureComponents-2' xsi:schemaLocation='urn:oasis:names:specification:ubl:schema:xsd:Invoice-2 HRInvoice.xsd' xmlns='urn:oasis:names:specification:ubl:schema:xsd:Invoice-2'>"
strXML = strXML & "        <ext:UBLExtensions>"
strXML = strXML & "          <ext:UBLExtension>"
strXML = strXML & "            <cbc:ID>HRINVOICE1</cbc:ID>"
strXML = strXML & "            <cbc:Name>InvoiceIssuePlaceData</cbc:Name>"
strXML = strXML & "            <ext:ExtensionAgencyID>MINGORP</ext:ExtensionAgencyID>"
strXML = strXML & "            <ext:ExtensionAgencyName>MINGORP</ext:ExtensionAgencyName>"
strXML = strXML & "            <ext:ExtensionAgencyURI>MINGORP</ext:ExtensionAgencyURI>"
strXML = strXML & "            <ext:ExtensionURI>urn:invoice:hr:issueplace</ext:ExtensionURI>"
strXML = strXML & "            <ext:ExtensionReasonCode>MandatoryField</ext:ExtensionReasonCode>"
strXML = strXML & "            <ext:ExtensionReason>Mjesto izdavanja raèuna prema Pravilniku o PDV-u</ext:ExtensionReason>"
strXML = strXML & "            <ext:ExtensionContent>"
strXML = strXML & "              <ext:InvoiceIssuePlace>MyTown</ext:InvoiceIssuePlace>"
strXML = strXML & "            </ext:ExtensionContent>"
strXML = strXML & "          </ext:UBLExtension>"
strXML = strXML & "        </ext:UBLExtensions>"
strXML = strXML & "     </Invoice>"
strXML = strXML & "   </InvoiceEnvelope>"
strXML = strXML & "  </OutgoingInvoice>"
strXML = strXML & "</OutgoingInvoicesData>"



    Url = "http://demo.webadress.com/apis/v2/send/"
    strUserName = "ThisIsTheUserName"
    strPassword = "PaSSworD"
    strCompanyId = "33122611302"
    strSoftwareId = "Test-001"


    strJSON = ""
    strJSON = strJSON & "{" & Chr(34) & "Username" & Chr(34) & ": " & strUserName & ","
    strJSON = strJSON & Chr(34) & "Password" & Chr(34) & ": " & Chr(34) & strPassword & Chr(34) & ","
    strJSON = strJSON & Chr(34) & "CompanyId" & Chr(34) & ": " & Chr(34) & strCompanyId & Chr(34) & ","
    strJSON = strJSON & Chr(34) & "SoftwareId" & Chr(34) & ": " & Chr(34) & strSoftwareId & Chr(34) & ","
    strJSON = strJSON & Chr(34) & "File" & Chr(34) & ": " & Chr(34) & strXML & Chr(34) & "}"



    objHTTP.Open "POST", Url, False

   objHTTP.setRequestHeader "Content-type", "application/json"
   objHTTP.send (strJSON)
   result = objHTTP.responseText


ExitSub:
    Set objHTTP = Nothing


End Sub
This line in XML triggers this error:
Code:
<ext:ExtensionReason>Mjesto izdavanja raèuna prema Pravilniku o PDV-u</ext:ExtensionReason>"
It contains a special character è

How could I convert the strJSON to UTF-8?