Following is the stack trace for the exception with DB2 database.
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2021 Jun 07 08:49:30:668 GMT -0400 BW.BusinessConnect-Interior_Server Error [bw.logger] BW-EXT-LOG-100000 Exception happen when access DB, message : One or more values in the INSERT statement, UPDATE statement, or foreign key update caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "1" constrains table "TIBPOD.BC_TRANSACTIONS" from having duplicate values for the index key.. SQLCODE=-803, SQLSTATE=23505, DRIVER=3.62.57. While executing : null
2021 Jun 07 08:49:30:668 GMT -0400 BW.BusinessConnect-Interior_Server Error [bw.logger] BW-EXT-LOG-100000 com.ibm.db2.jcc.am.SqlIntegrityConstraintViolationException: One or more values in the INSERT statement, UPDATE statement, or foreign keyupdate caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "1" constrains table "TIBPOD.BC_TRANSACTIONS" from having duplicate values for the index key.. SQLCODE=-803, SQLSTATE=23505, DRIVER=3.62.57
at com.ibm.db2.jcc.am.fd.a(fd.java:672)
at com.ibm.db2.jcc.am.fd.a(fd.java:60)
at com.ibm.db2.jcc.am.fd.a(fd.java:127)
at com.ibm.db2.jcc.am.jn.b(jn.java:2299)
at com.ibm.db2.jcc.am.jn.c(jn.java:2282)
at com.ibm.db2.jcc.t4.cb.k(cb.java:370)
at com.ibm.db2.jcc.t4.cb.a(cb.java:62)
at com.ibm.db2.jcc.t4.q.a(q.java:50)
at com.ibm.db2.jcc.t4.sb.b(sb.java:220)
at com.ibm.db2.jcc.am.kn.lc(kn.java:3077)
at com.ibm.db2.jcc.am.kn.b(kn.java:4034)
at com.ibm.db2.jcc.am.kn.dc(kn.java:746)
at com.ibm.db2.jcc.am.kn.executeUpdate(kn.java:729)
at com.tibco.ax.fw.db.DbAccess$1.update(DbAccess.java:258)
at com.tibco.ax.fw.db.DbAccess$DBUpdater.execute(DbAccess.java:2277)
at com.tibco.ax.fw.db.DbAccess.dispatchedLog(DbAccess.java:557)
at com.tibco.ax.fw.db.DbAccess.Log(DbAccess.java:151)
at com.tibco.ax.fw.db.AuditAccessImpl.auditLog(AuditAccessImpl.java:181)
at com.tibco.ax.fw.db.AuditAccessImpl.createOrUpdateAuditLog(AuditAccessImpl.java:230)
at com.tibco.ax.tibedi.runtime.pf.batch.AddTransaction.TxnAddedToBatchLog(AddTransaction.java:522)
at com.tibco.ax.tibedi.runtime.pf.batch.AddTransaction.Start(AddTransaction.java:137)
at com.tibco.ax.tibedi.runtime.pf.inbound.ProcessAck.addToSchdTask(ProcessAck.java:1052)
at com.tibco.ax.tibedi.runtime.pf.inbound.ProcessAck.IterateAckData(ProcessAck.java:588)

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This is a harmless exception that can happen when multiple engines try to insert first log of a batch,.  The failed engine will try to update the record rather than trying to insert. 

This exception will not impact any feature, and can be safely ignored.