No gadgets load in JIRA, unable to add new gadgets

Some users are experiencing a problem with JIRA gadgets, when effected no gadgets (except the Introduction gadget) load, and error messages are displayed:

"This gadget cannot be displayed on your dashboard. This could be due to a licensing problem or an application error. If you need this gadget, contact your administrator for assistance. Otherwise, you can remove it from your dashboard."

When attempting to add a new gadget to the dashboard, only the Introduction gadget is listed.

Errors appear in the logs for example:

/secure/Dashboard.jspa [c.a.g.renderer.internal.GadgetSpecFactoryImpl] Error occurred while retrieving gadget spec for rest/gadgets/1.0/g/com.atlassian.streams.streams-jira-plugin:activitystream-gadget/gadgets/activitystream-gadget.xml
/secure/Dashboard.jspa [c.a.g.embedded.internal.GadgetUrlBuilder] GadgetUrlBuilder: could not parse spec at rest/gadgets/1.0/g/com.atlassian.streams.streams-jira-plugin:activitystream-gadget/gadgets/activitystream-gadget.xml

Workaround

• Restart JIRA
• (JIRA Cloud customers should log a support ticket at https://support.atlassian.com to arrange a restart)

P.S: Instances affected by this bug have also reported problems on:

• Viewing agile boards with a filter with more than 1 project
• Service desk email handler can't retrieve emails (the connection log shows an error)