2. Fault Propagation from Child to Parent Activities

Date: 2025-04-01

Status

Accepted

Context

When an activity throws an exception during execution, the ExceptionHandlingMiddleware is responsible for handling the fault. In addition to logging the exception and recording an incident, it also explicitly faults all ancestor activities using the GetAncestors() method and calling TransitionTo(ActivityStatus.Faulted) on each one.

At the time of implementing this behavior, the rationale was likely to bubble up the fault status to allow Elsa Studio to display that a given activity has one or more faulting descendant activities.

However, this behavior causes unintended side effects when the faulted activity is later resumed and completes successfully. Since the parent (e.g., a Flowchart) was faulted earlier, it remains in a Faulted state, unaware that the child it depends on has now succeeded. As a result, the Flowchart itself never reaches Completed, and the entire workflow instance is stuck in Faulted or Running, depending on the selected fault strategy.

Decision

A new field will be introduced that represents an aggregate count of the faults occurring in descendant activities.

Consequences

• Allows composite activities to reflect a failed state immediately and consistently when one of their children fails.

Alternatives Considered

• Query descendants at runtime to get an aggregate fault count instead. However, this is an expensive operation that can be time consuming.