Veeam Backup for Nutanix AHV Proxy Appliance failure to update to v3

After installing Veeam Backup & Replication 11a (11.0.1.1261), one or more of the following may occur:

• An AHV Backup Proxy is listed as Unavailable in the Veeam Backup & Replication console.
• The AHV Backup Proxy's  Web Console dashboard lists the backup server as unavailable.
• Accessing the AHV Backup Proxy's Web Console results in a page that displays a 502 Gateway Timeout.
• The update wizard or the Veeam Updater displays an error stating, "Failed to update Ubuntu to version 18.04.6 LTS."
• AHV Backup jobs fail to run.
• Restoring to an AHV cluster is not possible.

After updating Veeam Backup & Replication to 11a, the AHV Backup Proxy is updated to Veeam Backup for Nutanix AHV v3. The AHV Backup Proxy update process updates the proxy components and the appliance's operating system from Ubuntu 16.04 LTS to 18.04 LTS. If the appliance operating system or one of the proxy components fails to update during this upgrade, it can leave the proxy in a malfunctioning state.

The following have been identified by Veeam Support to cause the described symptoms :

1. The software update removed some custom entries in the /etc/hosts file on the proxy.
2. Ubuntu failed to update to 18.04 LTS.
3. The Nginx component failed to update.

Find the scenario and solution described below that best fits your situation.
 

I. AHV Backup Proxy Web Console and Veeam Backup & Replication list each other as Unavailable

The AHV Backup Proxy cannot resolve the hostname of the Veeam Backup & Replication server to the correct IP address. If custom entries were added to the /etc/hosts file before the upgrade, they might need to be added again, as the Ubuntu OS update may have removed them. 

Check whether DNS servers are shown in the network configuration and if they are not - add them back. If they are not there, and the checkbox for automatic obtaining is ticked and greyed out - it helps to check-uncheck the same checkbox for IP-address parameters 1-3 times.

For more information, review Configuring Network Settings and Configuring Hostname Resolution in the Veeam Backup for Nutanix AHV 3.0 user guide.

II. The AHV Backup Proxy update displays an error message about being unable to download updates.

Ensure that the repositories listed in Used Ports can be reached by the AHV Backup Proxy, then rerun the update.

III. AHV Backup Proxy Web Console displays a 502 Gateway Timeout error

This typically means the update process failed. Reboot the proxy by going into Prism and choosing "Guest Reboot". If the 502 Gateway Timeout errors persist, you must deploy a new AHV Backup Proxy. Expand the section below, and follow the steps.