"Error while retrieving application rssnewsfeeds-4.0"

I have tried to deploy the below portlet in 5.0:

http://nightly.jahia.org/webapps/rssnewsfeeds-4.0.war

I did not get any errors during the deployment.

When I add the portlet to a page, I get this error:

"Error while retrieving application rssnewsfeeds-4.0"

When looking at the console, I see this error:

"Cannot save feeds: null"

Any thoughts on how to fix this problem?