Symptoms

When trying to add a plugin, you get the error, "An error was encountered while retrieving plugin details"

Cause

There may be a firewall or proxy proxy blocking the following URLs:

https://plugins.atlassian.com
https://marketplace.atlassinan.com

Workaround

You can upload the Plugin manually:

1. Download the plugin

2. Go to Administration Page - Plugins & Apps - Plugins

3. Go to Install tab - Upload Plugin (on the right)

4. Chose the plugin and click on upload}

Resolution

Ask your Network Administrator to allow access to the above URLs.