Flowable Dead letter job table exception extract from our UAT database

Hi Flow team, below are the Dead letter job exception data extract from one of our environment.
Randomly some times this dead letter job data is increasing, please help me to categorize this issue and how to fix these issues.

  1. “this activity isn’t waiting for a trigger” Their are almost thousands of this exception messages in Dead letter job table, what is the root cause for throwing this exception please help me to check this issue.

  2. For below messages i have created all these properties in process Data Object but still some this it will throw bleow error, please let me know how to fix this issues.

Unknown property used in expression: {ENV_NAME}_EXCEPTION_{LOCATION}
Unknown property used in expression: {RETRYCOUNT < SVC_MAXRETRY && SVC_DECISION != 'SUCCESS' && SVC_DECISION != 'ERROR'} Unknown property used in expression: {RETRYCOUNT== SVC_MAXRETRY}
Unknown property used in expression: ${SVC_INTERVAL}

  1. For below exception i don’t know the root cause, could you please help me to identify when below exception will be thrown. Even this is not occurring all the time only for some case it is throwing this exception.
    org.flowable.engine.impl.bpmn.behavior.ExclusiveGatewayActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior
    org.flowable.engine.impl.bpmn.behavior.InclusiveGatewayActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior
    org.flowable.engine.impl.bpmn.behavior.NoneEndEventActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior
    org.flowable.engine.impl.bpmn.behavior.ScriptTaskActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior
    org.flowable.engine.impl.bpmn.behavior.ServiceTaskDelegateExpressionActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior
    org.flowable.engine.impl.bpmn.behavior.UserTaskActivityBehavior cannot be cast to org.flowable.engine.impl.delegate.SubProcessActivityBehavior

Error Code must not be empty.
Error while evaluating expression: ${activityEvent}
Exception while invoking TaskListener: Exception while invoking TaskListener:
Execution[ id ‘049ba6b1-33b4-11e9-b4d9-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘049b584f-33b4-11e9-b4d9-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘260bba63-4181-11e9-992c-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘26096fcc-4181-11e9-992c-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘262d3500-33d8-11e9-b4d9-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘262ce69e-33d8-11e9-b4d9-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘367381fa-30c9-11e9-afa1-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘367381b8-30c9-11e9-afa1-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘438878bf-856c-11e9-b10c-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘43887818-856c-11e9-b10c-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘526484d1-7b2b-11e9-9775-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘5264842c-7b2b-11e9-9775-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘647ec48e-2ed2-11e9-916a-005056bb72e3’ ] - activity ‘scripttask1’ - parent ‘647ec44c-2ed2-11e9-916a-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘695c1bbf-338d-11e9-b4d9-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘695bcd5d-338d-11e9-b4d9-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘6e53b699-825d-11e9-8d97-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘6e53b5f1-825d-11e9-8d97-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘703904d7-7183-11e9-8258-005056bb72e3’ ] - activity ‘commit.process’ - parent ‘7039048b-7183-11e9-8258-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘7346936c-8098-11e9-8d97-005056bb72e3’ ] - activity ‘scripttask1’ - parent ‘734692c5-8098-11e9-8d97-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘77ad3b12-23a8-11e9-b02d-005056bb72e3’ ] - activity ‘scripttask1’ - parent ‘77aac9d0-23a8-11e9-b02d-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘a6a2618b-7fdd-11e9-8d97-005056bb72e3’ ] - activity ‘scripttask1’ - parent ‘a6a260e5-7fdd-11e9-8d97-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘a8647c07-3038-11e9-a512-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘a8620a6b-3038-11e9-a512-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘afd472ba-2ed8-11e9-916a-005056bb72e3’ ] - activity ‘scripttask1’ - parent ‘afd22888-2ed8-11e9-916a-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘b427a605-1ee2-11e9-83d9-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘b427a562-1ee2-11e9-83d9-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘b5ea677e-3160-11e9-82bf-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘b5ea673c-3160-11e9-82bf-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘c8dc3eff-86f4-11e9-b538-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘c8dc3e59-86f4-11e9-b538-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘e10a3e5b-83d8-11e9-b598-005056bb72e3’ ] - activity ‘servicetask1’ - parent ‘e107f3d3-83d8-11e9-b598-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘eee707b1-2fa8-11e9-a512-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘eee7076f-2fa8-11e9-a512-005056bb72e3’ was updated by another transaction concurrently
Execution[ id ‘f68d4b1e-34e9-11e9-b4d9-005056bb72e3’ ] - activity ‘copy.variables.to.parent’ - parent ‘f68cfdbc-34e9-11e9-b4d9-005056bb72e3’ was updated by another transaction concurrently
Expected one result (or null) to be returned by selectOne(), but found: 2
Expected one result (or null) to be returned by selectOne(), but found: 3
HistoricActivityInstanceEntity[id=59139756-17e0-11e9-b9ae-005056bb72e3, activityId=nbreject, activityName=Reject Process, executionId= 33b8e191-1572-11e9-9f27-005056bb72e3] was updated by another transaction concurrently
HistoricVariableInstanceEntity[id=edbbce86-2fa8-11e9-a512-005056bb72e3, name=UWSUPPORTTRIGGER3, revision=0, type=string, textValue=] was updated by another transaction concurrently
UserTask should not be signalled before complete