OEM 13.2 Exported Ruleset Failed with 'Error in parsing properties for RuleSet from the XML' when Importing into EM 13.x

When importing ruleset in Enterprise Manager 13.x (confirmed in 13.2 and 13.4) from xml file exported from Enterprise Manager 13.2, got following error,

  Error in parsing properties for RuleSet from the XML

If the destination EM version is 13.2, following message will be found from trace file emoms.trc under directory <OMS_INSTANCE_BASE>/em/EMGC_OMS1/sysman/log

2021-03-29 22:49:12,394 [[ACTIVE] ExecuteThread: '7' for queue: 'weblogic.kernel.Default (self-tuning)'] ERROR exportimport.ImportHelper logp.251 - Error in parsing properties for RuleSet from the XML
oracle.sysman.emSDK.app.exception.EMSystemException
     at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesModelUtil.throwEMSystemException(RulesModelUtil.java:1486)
     at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.postChanges(RulesFwkEntityImpl.java:116)
     ...
    ... 100 more
Caused by: oracle.jbo.JboException: JBO-29000: Unexpected exception caught: oracle.jbo.DMLConstraintException, msg=JBO-26048: Constraint "EM_RULE_EXPRESSIONS_UK1" is violated during post operation "Insert" using SQL statement "INSERT INTO EM_RULE_EXPRESSIONS(SELECTION_OBJECT_ID,EXPRESSION_ID,EXPRESSION_GROUP_ID,ATTR_ID,OPERATOR_CODE,ATTR_VALUE,SEL_OBJ_TYPE,EXPRESSION_TYPE,UI_GROUP_ID,EXCLUSION_GROUP_ID) VALUES (:1,:2,:3,:4,:5,:6,:7,:8,:9,:10)".
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.doDML(RulesFwkEntityImpl.java:201)
    at oracle.jbo.server.EntityImpl.postChanges(EntityImpl.java:7271)
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.postChanges(RulesFwkEntityImpl.java:97)
    ... 104 more
Caused by: oracle.jbo.DMLConstraintException: JBO-26048: Constraint "EM_RULE_EXPRESSIONS_UK1" is violated during post operation "Insert" using SQL statement "INSERT INTO EM_RULE_EXPRESSIONS(SELECTION_OBJECT_ID,EXPRESSION_ID,EXPRESSION_GROUP_ID,ATTR_ID,OPERATOR_CODE,ATTR_VALUE,SEL_OBJ_TYPE,EXPRESSION_TYPE,UI_GROUP_ID,EXCLUSION_GROUP_ID) VALUES (:1,:2,:3,:4,:5,:6,:7,:8,:9,:10)".
    at oracle.jbo.server.OracleSQLBuilderImpl.doEntityDML(OracleSQLBuilderImpl.java:565)
    at oracle.jbo.server.EntityImpl.doDML(EntityImpl.java:9098)
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.doDML(RulesFwkEntityImpl.java:196)
    ... 106 more
Caused by: java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (SYSMAN.EM_RULE_EXPRESSIONS_UK1) violated

If the destination EM version is 13.4 (or 13.3), following message will be found from trace file emoms.trc

2021-03-29 22:04:29,284 [[ACTIVE] ExecuteThread: '70' for queue: 'weblogic.kernel.Default (self-tuning)'] ERROR exportimport.ImportHelper logp.251 - Error in parsing properties for RuleSet from the XML
oracle.sysman.emSDK.app.exception.EMSystemException
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesModelUtil.throwEMSystemException(RulesModelUtil.java:1509)
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.postChanges(RulesFwkEntityImpl.java:106)
    ...
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:420)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:360)
Caused by: oracle.jbo.RowAlreadyDeletedException: JBO-25019: Entity row with key oracle.jbo.Key[BEB7FD94E2112377E053DA570F89CC8F ] is not found in EmRuleSetsEO.
    at oracle.jbo.server.OracleSQLBuilderImpl.doEntitySelectForAltKey(OracleSQLBuilderImpl.java:811)
    at oracle.jbo.server.BaseSQLBuilderImpl.doEntitySelect(BaseSQLBuilderImpl.java:554)
    at oracle.jbo.server.EntityImpl.doSelect(EntityImpl.java:9133)
    at oracle.jbo.server.EntityImpl.lock(EntityImpl.java:6612)
    at oracle.jbo.server.EntityImpl.beforePost(EntityImpl.java:7150)
    at oracle.jbo.server.EntityImpl.postChanges(EntityImpl.java:7384)
    at oracle.sysman.core.event.rules.uimodel.rulesfwk.RulesFwkEntityImpl.postChanges(RulesFwkEntityImpl.java:97)
    ... 95 more

It is a bug of EM 13.2, it can be fixed by apply OMS one-off patch 25986453 on source EM 13.2. The patch is also needed for destination EM if the version is 13.2.