---
alias: user-guide-business-workflow-task-protocol-instance-open-pre
render_macros: false
description: "Starts a workflow before a protocol instance is opened."
---

# Before Protocol Instance Opening

Starts a workflow before a **Protocol Instance** is opened.

![Screenshot of a Business Workflow using If and Throw error to require Materials before opening a Protocol Instance.](images/business-workflow-task-protocol-instance-open-pre.png)

## Event Context

The event provides `Protocol`, `ProtocolInstance`, `Materials`, `MaterialComments`, `OperationAttributes`, `RuleInputs`, `Parameters` to tasks in its branch. Select these values in the value editor when configuring child tasks.

??? example "Before Protocol Instance Opening"

    Inspect the proposed protocol-opening context and reject an opening that violates the workflow's rule.

## Behavior

The handler runs inside the operation's transaction. An error in the handler can cancel or roll back the operation. An After event runs after the operation boundary, while the transaction is still active.