There is an error in XML document (1, 451).

Question

XML Document

<?xml version='1.0' encoding='UTF-8'?>
                <soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/' 
                xmlns='urn:enterprise.soap.sforce.com' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' 
                xmlns:sf='urn:sobject.enterprise.soap.sforce.com'><soapenv:Body><queryResponse><result>
                <done>true</done><queryLocator xsi:nil='true'/><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>No</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>No</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c></records><records xsi:type='sf:Contact_Transaction__c'>
                <sf:Id xsi:nil='true'/><sf:Is_in_SLA__c>Yes</sf:Is_in_SLA__c>
                </records><size>11</size></result></queryResponse></soapenv:Body></soapenv:Envelope>

Answer 1

The document looks well formed to me. Do you mean there is an error when validating the XML or when some service processes it? All I can gather from what you posted is that you're using Salesforce in some way. Please read the Tips on Posting Good Questions.