Unable to advance to next challenge with Ctrl-K in FreeCodeCamp

[dancaunt]

Push, Pull, and Submit work as expected with Ctrl-H, Ctrl-L, and Ctrl-J. But when I use Ctrl-K to advance to the next challenge in FreeCodeCamp, nothing happens in the browser and the I get the following error on the terminal:

{"id":1,"result":{"result":{"type":"object","subtype":"error","className":"TypeError","description":"TypeError: Cannot read property 'click' of null\n at <anonymous>:1:42","objectId":"{\"injectedScriptId\":9,\"id\":1}"},"exceptionDetails":{"exceptionId":11,"text":"Uncaught","lineNumber":0,"columnNumber":41,"scriptId":"471","stackTrace":{"callFrames":[{"functionName":"","scriptId":"471","url":"","lineNumber":0,"columnNumber":41}]},"exception":{"type":"object","subtype":"error","className":"TypeError","description":"TypeError: Cannot read property 'click' of null\n at <anonymous>:1:42","objectId":"{\"injectedScriptId\":9,\"id\":2}"}}}}

I'm using Ubuntu 16.04 and Python 3.5.2 in a Conda virtual environment.