#!/bin/bash
s='2021-10-07 10:32:05,767 ERROR [LAWT2] blah.blah.blah - Message processing FAILED: <ExecutionReport blah="xxx" foo="yyy" SessionID="kkk" MoreStuff="zz"> Total time for which application threads were stopped: 0.0003858 seconds, Stopping threads took: 0.0000653 seconds
2021-10-07 10:31:32,902 ERROR [LAWT6] blah.blah.blah - Message processing FAILED: <NewOrderSingle SessionID="zkx" TargetSubID="ttt" Account="blah" MsgType="D" BookingTypeOverride="0" Symbol="6316" OtherField1="othervalue1" Otherfield2="othervalue2"/></D></NewOrderSingle>'
perl -ne '/\h(SessionID=".*?")?(?:\h++.*(MsgType=".*?"))?\h/ and print "$1|$2\n"' <<< "$s"

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