We identified an issue with the current Flowable process definitions on cloud env related to empty <errorEventDefinition/> elements in BPMN end events.
Problem:

In some deployed process definitions, end events had <errorEventDefinition/> without an errorRef.

Flowable requires an error code for error end events.

When these processes are executed, the following exception occurs:

org.flowable.common.engine.api.FlowableIllegalArgumentException: Error Code must not be null
at org.flowable.engine.delegate.BpmnError.setErrorCode(BpmnError.java:53)
at org.flowable.engine.delegate.BpmnError.<init>(BpmnError.java:48)
at org.flowable.engine.impl.bpmn.behavior.ErrorEndEventActivityBehavior.execute(ErrorEndEventActivityBehavior.java:48)

Root Cause:

Flowable engine requires all <errorEventDefinition/> elements to have a valid errorRef.

Some older BPMN files were deployed without a global error or without specifying errorRef on end events.