Symptoms

When attempting to use the UPM, a java.net.UnknownHostException is thrown, as in the screenshot below:

Diagnosis

The error occurred in JIRA 4.4.5, using the Universal Plugin Manager v1.4.1. It will likely be present in other versions of JIRA and also the UPM.

Cause

The Universal Plugin Manager is unable to establish an outbound connection to the Atlassian Marketplace. The most likely cause for this is the JIRA instance does not have an outbound connection to the Information Superhighway or is using an internal DNS that does not have plugins.atlassian.com in it.

Resolution

This can be resolved with any of the following:

• Disable network access to the Marketplace, as in Problems Connecting to the Atlassian Marketplace.
• Set up JIRA to use an outbound proxy as per our Configure an outbound proxy for use in Jira server KB article.
• Update the UPM to the latest version manually, using our Installing a plugin manually docs and downloading the appropriate version of the UPM from the Atlassian Marketplace.
  Later versions of the UPM handle this use case better and allow for network access to be disabled through the plugin itself.