Examples fail on binder and local. Script error for "ipyevents"

[mforbes]

When I try to launch the examples on BinderHub or on may local computer, the examples do not work.

Looking at the JS Console, I see the following error:

manager-base.js:575 Error: Script error for "ipyevents"
http://requirejs.org/docs/errors.html#scripterror

Any ideas what is going wrong or how to fix it?

Details

manager-base.js:575 Error: Script error for "ipyevents"
http://requirejs.org/docs/errors.html#scripterror
    at makeError (require.js?v=d37b48bb2137faa0ab98157e240c084dd5b1b5e74911723aa1d1f04c928c2a03dedf922d049e4815f7e5a369faa2e6b6a1000aae958b7953b5cc60411154f593:168:17)
    at HTMLScriptElement.onScriptError (require.js?v=d37b48bb2137faa0ab98157e240c084dd5b1b5e74911723aa1d1f04c928c2a03dedf922d049e4815f7e5a369faa2e6b6a1000aae958b7953b5cc60411154f593:1735:36)
loadModelClass @ manager-base.js:575
await in loadModelClass (async)
_make_model @ manager-base.js:402
new_model @ manager-base.js:245
handle_comm_open @ manager-base.js:155
(anonymous) @ comm.js:89
Promise.then (async)
CommManager.comm_open @ comm.js:85
i @ jquery.min.js:2
Kernel._handle_iopub_message @ kernel.js:1239
Kernel._finish_ws_message @ kernel.js:1018
(anonymous) @ kernel.js:1009
Promise.then (async)
Kernel._handle_ws_message @ kernel.js:1009
i @ jquery.min.js:2