The **Lock** block locks the desktop session for the user account running on the Agent machine. It is typically used to simulate real-world security scenarios, or to reset session state between test cases.

Once triggered, the block attempts to perform a system lock within a given timeout period.

Fully expanded, the Lock building block shows the following properties:

**Note:** The screenshot on this page uses the **Elegance Design**, introduced in **2025.3**. If you are using an earlier version, your layout may look different.

## Quick-start

1. Drag **Lock** onto the canvas.
2. Connect the block in the flow and optionally specify **Timeout (sec)**.
3. Run the flow when it’s ready.

## Building block parameters

Parameters

- **Block header**: The block title (“Lock”) can be renamed by double-clicking it and typing in a new title.

- **Failed**: Triggers if locking the system is not completed within the configured timeout.

- **Timeout (sec)**: The maximum time the block will spend performing the lock operation before triggering **Failed**.

## Resources

| **Topic** | **Description** |
| --- | --- |
| [Flows FAQ](https://docs.leapwork.com/faq/latest/leapwork-flow-faq/flows-faq) | Common questions about creating, running, and managing flows in Leapwork. |
| [Flows Troubleshooting](https://docs.leapwork.com/troubleshooting/latest/leapwork-flow-troubleshooting/flows-troubleshooting) | Guidelines and solutions for identifying and fixing issues that occur when building or running flows in Leapwork.