Misusing Events: Starts, Ends, and Intermediates

Getting event modeling right early saves hours of rework later. A single misused event can change how a process is interpreted by developers, auditors, or business users. I’ve seen teams ship automation based on diagrams where the start event was a generic “Start” symbol — no trigger, no context, no clarity. The result? The system launched processes at random times. That’s not just a modeling flaw. It’s a risk.

Too many practitioners treat events as decorative. But every event defines intent. A start event signals the trigger. An end event defines the conclusion. Misuse here distorts the entire process scope.

This chapter breaks down the most common BPMN event mistakes — not just how to spot them, but how to fix them with a clear, repeatable method. You’ll learn how to choose the right BPMN event type, assign unambiguous names, and avoid misleading patterns that confuse automation and auditing.

Start and End Event Errors: The Silent Triggers of Misinterpretation

Start and end events are not just visual cues. They define the process boundary. A missing start event makes a process ambiguous — it could trigger from anywhere.

Similarly, an end event with no meaning doesn’t signal completion. It’s like a door with no exit. The process might appear to end, but the system doesn’t know when it’s truly done.

Common Start Event Mistakes

• Using a generic “Start” symbol without specifying a trigger.
• Adding multiple start events without clear separation of scenarios.
• Using a plain start event for a process that should only begin on message receipt.

Here’s a real example: a team modeled a customer onboarding process with a start event labeled “Start.” No trigger. No context. The automation tool assumed it was always ready. In reality, it only started when a customer submitted a form. The gap between intent and behavior caused delays and misaligned expectations.

End Event Confusion: When “End” Isn’t Final

End events aren’t just decorative. They define what “done” means. A process can end in multiple ways: normally, due to error, or through termination.

Using a terminate end event without clarity creates unintended consequences. Termination doesn’t mean “finish.” It means “stop everything immediately.” One such case: a loan approval process used a terminate end event after approval. When the process was terminated, downstream systems had no record of approval — and no audit trail.

Choosing the Right BPMN Event Types

Picking the wrong event type is a silent error. It may pass validation, but it misrepresents business intent. Let’s break down the most common confusions.

Message vs. Timer vs. Error Events

Each event type carries a distinct semantic meaning. Confusing them leads to incorrect automation and unpredictable behavior.

Here’s a decision table to guide your choice:

Trigger	Recommended Event Type	When to Use
A customer submits a form	Message start event	Process begins via external message
One hour after submission	Timer event	Process begins after delay
An error occurs in a step	Error end event	Process terminates due to exception
System failure or shutdown	Terminate end event	Immediate process cancellation

Rule of thumb: the event type must match the trigger. Not the label. The behavior.

How to Use BPMN Events Correctly

1. Define the trigger first. Ask: What causes this process to start or end?
2. Match the event type to the trigger. Use message for external signals, timer for time-based triggers, error for exceptions.
3. Name with intent. Instead of “Start” or “End,” use “Customer submits form” or “Approval rejected.”
4. Use only one start event per scenario. If multiple triggers exist, use multiple processes or separate events with clear labels.
5. Avoid terminate end events unless necessary. They bypass normal flow and can leave side effects unlogged.

Consider this: a process to handle customer complaints. The start event should be “Customer submits complaint via portal.” Not “Start.” The name is not decorative. It’s a contract.

Overusing Terminate End Events: The Hidden Risk

Terminate end events are powerful — but dangerous. They stop the entire process immediately, skipping all intermediate steps, including cleanup and notifications.

Common mistake: using a terminate end event in a process that handles data reconciliation. When an error occurs, the process terminates — but the data remains inconsistent, and no one is notified.

Instead, use:

• Error end event — for handling exceptions in a controlled way.
• Cancel end event — for processes that can be canceled gracefully (e.g., a reservation).
• Compensation event — for reversing prior actions.

Termination should be reserved for exceptional cases — like a system shutdown — where no cleanup is possible.

Event Naming: Intent Over Convention

Bad names: “Start,” “End,” “Event 1.” These are meaningless in context.

Good names: “Customer submits application,” “System receives order from partner,” “Error in payment validation.”

Use the verb–object format. Be specific. Include the actor if relevant. The goal is to make the event self-explanatory — even to someone who didn’t create the diagram.

Do’s and Don’ts of Event Naming

• Do name events with the trigger: “Customer submits form”
• Do include the source: “System receives API call from partner”
• Don’t use generic terms: “Start,” “End,” “Event”
• Don’t name after a system action: “Update database” — that’s a task, not a trigger

Naming isn’t just about clarity. It’s about ensuring correct automation. A poorly named event can lead to incorrect process mapping in a workflow engine.

Practical Checklist: Validating Event Modeling

Before finalizing any process, run this quick audit:

• Does every process have exactly one start event?
• Is the start event type correct for the trigger?
• Does the end event reflect the actual process conclusion?
• Is a terminate end event used only when immediate cancellation is required?
• Are all event names clear, specific, and action-based?
• Are there multiple start events? If yes, are they clearly separated by scenario?

These checks prevent 90% of event-related errors. They’re quick, repeatable, and work in any modeling tool.

Frequently Asked Questions

What happens if I don’t use a start event in my BPMN process?

Without a start event, the process has no defined trigger. Most workflow engines will reject it or assume an implicit start — which leads to unpredictable behavior. Always define the trigger explicitly.

Can I have multiple start events in one process?

Yes — but only if they represent distinct, independent scenarios. For example, “Customer submits form” and “Email notification received.” Use separate start events with clear labels. Don’t use multiple starts for the same process.

When should I use a timer start event instead of a message start event?

Use a timer start event when the process begins after a delay (e.g., “Send reminder after 48 hours”). Use a message start event when the process is triggered by an external system or user input (e.g., “Order received via API”). The key is whether the trigger is time-based or event-based.

Is it a problem to use a message start event for a system-generated process?

Not inherently. But ensure the message is sent by a recognized external source — a user, an external system, or a scheduled task. If the system itself initiates the process, use a timer or a call activity. Avoid self-triggering start events.

Why should I avoid terminate end events?

Terminate end events bypass normal flow and can leave systems in an inconsistent state. They’re not failure-safe. Use error, cancel, or compensation events instead unless you’re certain immediate termination is correct.

How do I know which event type to use for a business rule?

Start events should reflect the trigger: message (external input), timer (time-based), error (exception), or conditional (business rule). The event type must align with the actual cause. Don’t use a timer event just because a rule runs every hour — that’s a workflow, not a trigger. Use a message or timer event only if the process starts due to that event.