Agile Wallboard stopped working

Problem

Since the latest OnDemand Release (JIRA Agile 6.5.20), the Agile Wallboard Gadget stopped working.

When adding that gadget and configuring it (choosing the board, quick filters and refresh interval), clicking on "Save" does nothing:

Checking the dashboard, a blank gadget is displayed:

Symptoms

• JIRA Agile Wallboard gadget does not load
• Errors in the browser Javascript console

Uncaught TypeError: Cannot read property 'extend' of undefined com.pyxis.greenhopper.jira:gh-dialog.js?locale=en-US:6
Uncaught TypeError: undefined is not a function com.pyxis.greenhopper.jira:gh-rapid.js?locale=en-US:4147
Uncaught TypeError: Cannot read property 'getMode' of undefined com.pyxis.greenhopper.jira:gh-rapid.js?locale=en-US:4087
Uncaught TypeError: Cannot read property 'setPerViewValue' of undefined 

Work around

Unfortunately there is no work around at this time. In the absence of a working Wallboard Gadget, if you need to access a particular board and can do so outside of a Dashboard, please use that instead. "Projector mode" (press the Z key twice) helps to remove the outer chrome of the board page to maximise the viewing area on a wallboard.