The Salesforce Technology team has resolved a service disruption impacting a subset of Pardot accounts from 14:47 to 15:53 UTC. During this time the Pardot application was unavailable. As of 15:53 UTC the issue has been resolved and the application is available to all users.
Please contact Support at http://success.pardot.com
if you encounter any further issues. We sincerely regret any inconvenience you have experienced as a result of this incident