ServerComm.js:417 Uncaught TypeError: Cannot read property 'handler' of undefined
    at constructor._cancellationProcessed (ServerComm.js:417)
    at constructor._dispatch (ServerComm.js:819)
    at constructor._onRequestComplete (ServerComm.js:783)
    at Object.callback (ext-all-debug.js:9249)
    at constructor.onComplete (ext-all-debug.js:27343)
    at constructor.onStateChange (ext-all-debug.js:27300)
    at ext-all-debug.js:27290
    at Object.elevate (ext-all-debug.js:2552)
    at XMLHttpRequest.<anonymous> (ext-all-debug.js:27289)