Page gadgets fail with an internal server error

Page gadgets embedded in Jira were broken by the upgrade of the latest milestone release. Gadgets embedded in Confluence were not broken.

The gadgets in JIRA display the following error:

An internal server error occurred when requesting resource https://extranet.atlassian.com/rest/gadget/1.0/currentUser.

Rated as critical because it constitutes a loss of data for the user who was relying on seeing their Confluence data in JIRA.

Screenshot is attached.