Description of problem:

Sometimes I am unable to switch task to Completed state (javascript), button doesn't respond and following error appears in the browser error console:

Error: Ajax is not defined
Source File: https://tcms.engineering.redhat.com/media/js/lib/livepipe/lib/prototype.js
Line: 1485

  respondToReadyState: function(readyState) {
    var state = Ajax.Request.Events[readyState], response = new Ajax.Response(this);
  ...

Version-Release number of selected component (if applicable):


How reproducible:
sometimes, now idea why it happens
The only solution is completely shut down the browser and load the page again.

Steps to Reproduce:
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Actual results:
buttons not working

Expected results:


Additional info: