Error: ORA-01427: Single-Row Subquery Returns More Than One Row

Symptom

Excerpt from the systemout.log

insert into reorderpad (prqty, poqty, reorderqty, reservedqty, explotqty, curbal, orgid, siteid, usrname, itemnum, itemsetid, location, vendor, manufacturer, modelnum,
catalogcode, minlevel, orderqty, orderunit, deliverytime, gldebitacct, glaccount, linetype, inspectionrequired, mktplcitem, storeloc, storelocsite,consignment, shippedqty)
select 0, 0, 0, 0, 0, 0,  'EAGLENA' ,  'BEDFORD' ,  'ITEMSET1' ,itemnum, itemsetid,location, vendor, manufacturer, modelnum,
catalogcode, minlevel, orderqty, orderunit, deliverytime, controlacc, glaccount, 'ITEM' , 0, 0, storeloc, storelocsiteid,consignment,0
from inventory where (((status != 'OBSOLETE' and category = 'STK' and siteid = 'BEDFORD')) and (exists (select 1 from item where itemnum = inventory.itemnum and itemtype in (select value from synonymdomain where domainid='ITEMTYPE' and maxvalue = 'ITEM'))) and location= 'CENTRAL'  and siteid =  'BEDFORD'  and itemnum in (select itemnum from item where itemtype in (select value from synonymdomain where domainid = 'ITEMTYPE' and maxvalue = 'ITEM')) and status in ( 'ACTIVE' ,  'PLANNING' ) and reorder=1 and orderqty >0)

update reorderpad set    lottype=(select lottype from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
    description=(select description from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
    in19=(select in19 from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
     in20=(select in20 from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
    in21=(select in21 from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
    in22=(select in22 from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid),
    in23=(select in23 from item where item.itemnum=reorderpad.itemnum and item.itemsetid=reorderpad.itemsetid)
where usrname= 'MAXADMIN'  and location= 'CENTRAL' and itemnum is not null and siteid= 'BEDFORD' 

 
java.sql.SQLException: ORA-01427: single-row subquery returns more than one row
 
                at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:70)
                at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:131)
                at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:204)
                at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:455)
                at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:413)
                at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:1034)
                at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:183)
                at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:942)
                at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1222)
                at oracle.jdbc.driver.OracleStatement.executeUpdateInternal(OracleStatement.java:1706)
                at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:1674)
                at oracle.jdbc.driver.OracleStatementWrapper.executeUpdate(OracleStatementWrapper.java:275)
                at psdi.mbo.DBShortcut.execute(DBShortcut.java:177)
                at psdi.app.inventory.ReorderService.copyFromInvCost(ReorderService.java:1690)
                at psdi.app.inventory.ReorderService.addStoreRoomParts(ReorderService.java:1481)
                at psdi.app.inventory.ReorderService.getReorderSet(ReorderService.java:612)
                at psdi.app.inventory.ReorderService.getReorderSet(ReorderService.java:1025)
                at psdi.app.inventory.virtual.ReorderItemsSet.execute(ReorderItemsSet.java:176)
                at psdi.webclient.beans.common.ReorderBean.reorderpad(ReorderBean.java:87)
                at psdi.webclient.beans.common.ReorderBean.reorderpaditem(ReorderBean.java:208)
                at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
                at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
                at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
                at java.lang.reflect.Method.invoke(Method.java:611)
                at psdi.webclient.system.session.AsyncProcess.run(AsyncProcess.java:144)
                at java.lang.Thread.run(Thread.java:738)