> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aviatrix.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Upgrade Checklist of the Controller and Gateway Upgrade

> This topic provides an overview of the upgrade to-do list of the tasks before you begin your upgrade, during your upgrade, and after the upgrade.

This topic provides an overview of the upgrade to-do list of the tasks before
you begin your upgrade, during your upgrade, and after the upgrade.

Before the Controller and Gateway Upgrade, perform the following steps:

## Perform the Pre-upgrade Tasks for Controller and Gateways

Perform all the <a href={"/docs/enterprise/" + "10.1" +
"/guides/maintenance/controller-upgrade-planning"}>Pre-upgrade Tasks for
Controller and Gateways</a> before your upgrade.

## Understanding the Release Contents

To understand the contents and potential impact of upgrading to a specific
software release, see <a href={"/docs/enterprise/" + "10.1" +
"/reference/release-notices/release-notes/controller-images/index"}>Aviatrix
Controller and Gateway Image Release Notes</a>.

To understand the contents and potential impact of upgrading to a specific image
release, see <a href={"/docs/enterprise/" + "10.1" +
"/reference/release-notices/release-notes/controller-images/index"}>Aviatrix
Controller and Gateway Image Release Notes</a>.

### Verify DNS Settings

The Aviatrix Controller must have a reliable DNS resolution service available.
Aviatrix recommends using the default 8.8.8.8 for the DNS IP address. Using the
default address is not required, but your network must be able to resolve public
names and have uninterrupted access to the DNS name resolver.

#### AWS and Azure DNS Settings

If the Controller is running on AWS or Azure, you can go to the controller
Settings for the DNS and Disable the VPC or VNET DNS Server to force the
Controller to use 8.8.8.8.

## Verify Public Internet Access

Verify access to the public internet from the Aviatrix Controller. The
Controller must be open for inbound traffic on port 443 and outbound traffic on
port 22. Aviatrix recommends you enable security groups to restrict access. Go
to the Network tab on the Diagnostics page under Troubleshooting and perform the
following tasks.

* Ping a widely known public hostname or IP address with the Controller Utility.
* Ping security.aviatrix.com from the TCP/443 port with the Network Connectivity
  Utility.
* Ping [www.github.com](http://www.github.com) from the TCP/443 port with the Network Connectivity
  Utility.
* Ping [www.github.com](http://www.github.com) from outbound TCP/22 on Controller with the Network
  Connectivity Utility.

## Verify Account Permissions and Access

Go to the Accounts page and perform the following tasks.

* Go to the Accounts Audit tab under Accounts and perform an Account Audit.
  Correct any reported issues.
* Verify all accounts can access all connected cloud resources.
* Verify the Aviatrix primary access account is available and that the account
  credentials are valid.
* The IAM policies must be configured as recommended by Aviatrix. For more
  information, see Controller Instance Requirements.
* If you are migrating your Aviatrix Platform Controller to a new image, verify
  the new image has all required accounts and permissions before migrating the
  Controller. If you are restoring an image from a backup, the required accounts
  and permissions should all be available. Migration operations fail if there is
  not at least one Aviatrix backup file available.

## Verify Controller and Gateway Status

Go to the Controller Dashboard and check the status of the Aviatrix Platform
Controller and gateways.

* Verify all gateways are up and the status is green.
* Verify all tunnels are up and the status is green.

## (AWS Specific) Upgrade Checklist

### Verify Controller HA Version

You should be running the latest version of the Controller HA application before
upgrading. If there is a newer version of Controller HA available, you should
upgrade by disabling and re-enabling the Controller HA feature. For more
information, see <a href={"/docs/enterprise/" + "10.1" +
"/guides/controlplane/controller-ha-aws"}>AWS High Availability</a>.

### Verify Controller HA is Disabled

If you use Controller HA you will need to disable your HA configuration before
upgrading Controller. If you do not disable Controller HA before upgrading, the
system deploys a new Controller and restores the most recent backup.

### Settings for t2 and t3 Instances

If your Aviatrix Controller is in AWS and running on a t2 or t3 instance type
and you are planning a platform image upgrade, you must set the T2/T3 Unlimited
attribute to enabled. For more information, see
[Unlimited mode concepts](https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/burstable-performance-instances-unlimited-mode-concepts.html).