# On-demand Tasks - Endpoint Central Agent Unavailable

## Problem

You cannot complete any one of the following on-demand tasks:

- Scanning for patches
- Scanning for inventory
- Establishing remote control
- Moving agents from one remote office to another

The error message on the screen is **"Agent is not reachable"**.

## Cause

You will get this error message in the following cases:

- Computers could be:
  - In hibernate mode
  - In stand-by mode
  - Shut down
  - Disconnected from the network
- Communication cannot be established between the agent and the server

## Resolution

You are required to identify why you cannot install an agent. Follow one of the solutions given below, depending on what the problem is.

### Computers are in hibernate, sleep mode or shut down

Ensure that the computers, in which you want to start the on-demand tasks, are switched on.

### Computers are not in the network

Ensure that the computers, in which you want to start the on-demand tasks, are available in the network. Check the following:

- Network-cable connection
- Status of the computers. For example, if the computer is shut down, switch it on.

### Establishing agent-server communication

Establish access with the central server from the computer in which the agent is installed. The central server has a component called the notification server. Agents communicate with this server to get information regarding on-demand tasks.

Ensure that you have opened port **8027** to communicate with the notification server in the following:

- Network firewall
- Proxy (if any)
- Central server firewall

You can view the port number of the notification server at **Admin** > **Server Settings**.

**Applies to:** Agent availability, On-demand tasks  
**Keywords:** Agent availability, On-demand task failure, Agent unavailable

## Related Resources

### Other KB articles

- [Agent Installation](https://www.manageengine.com/products/desktop-central/knowledge-base.html#agent-installation)
- [Configurations](https://www.manageengine.com/products/desktop-central/knowledge-base.html#windows-configurations)
- [Inventory Management](https://www.manageengine.com/products/desktop-central/knowledge-base.html#inventory-management)
- [Patch Management](https://www.manageengine.com/products/desktop-central/knowledge-base.html#patch-management)
- [Software Distribution](https://www.manageengine.com/products/desktop-central/knowledge-base.html#software-distribution)
- [Service Pack Installation](https://www.manageengine.com/products/desktop-central/knowledge-base.html#service-pack-installation)
- [Desktop Sharing](https://www.manageengine.com/products/desktop-central/knowledge-base.html#remote-desktop-sharing)
- [Active Directory Reports](https://www.manageengine.com/products/desktop-central/knowledge-base.html#active-directory-reports)
- [User Logon Reports](https://www.manageengine.com/products/desktop-central/knowledge-base.html#user-logon-reports)
- [Endpoint Central SP Upgrade](https://www.manageengine.com/products/desktop-central/knowledge-base.html#service-pack-upgrade)
- [Miscellaneous](https://www.manageengine.com/products/desktop-central/knowledge-base.html#miscellaneous)
- [» More](https://www.manageengine.com/products/desktop-central/knowledge-base.html)

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Email: [desktopcentral-support@manageengine.com](mailto:desktopcentral-support@manageengine.com)

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