Error: mismatched tag at line 1, column 1101, byte 1101 at /usr/lib64/perl5/XML/Parser.pm line 187

Wait, are you putting $password in the body of the XML as well as in the auth header? Probably best to output the XML so you can see where the malformation occurs (ie. what's at byte 1101).

No, i tried passing my password in header and even then i got same error. There isnt much in xml.

        <?xml version="1.0" encoding="UTF-8"?>
           <soap:Envelope
                  xmlns:soap="http://www.w3.org/2003/05/soap-envelope"
                  xmlns:urn="urn:com:document:rfc:functions">
      <soap:Header/>
         <soap:Body>
            <urn:_-A1SSPC_-SPC_INCIDENT_CREATION>
            <IV_CHECK_GROUP>value</IV_CHECK_GROUP>
            <IV_CHECK_ID>value</IV_CHECK_ID>
            <IV_EVENT_KEY>value</IV_EVENT_KEY>
            <IV_DESCRIPTION>************* Alert Details *************
 
Description
    </IV_DESCRIPTION>
            <IV_INCIDENT_PROCESS>SYSTEM INCIDENT</IV_INCIDENT_PROCESS>
            <IV_ISSUE_CATEGORY>30042</IV_ISSUE_CATEGORY>
            <IV_TEAM>CF_IOT</IV_TEAM>
            <IV_PRIORITY>3</IV_PRIORITY>
            <IV_TENANT_ID>000000000000000001</IV_TENANT_ID>
            <IV_PROCESS>32</IV_PROCESS>
            <IV_SUBJECT>subject</IV_SUBJECT>
         </urn:_-A1SSPC_-SPC_INCIDENT_CREATION>
      </soap:Body>
   </soap:Envelope>
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That isn't the XML you are sending because it has fewer than 1100 characters (and more than 1 line). Compare the payload at both ends and on the wire if you can. That should show you where the problem really lies.