JS TypeError: Cannot read property 'length' of undefined on loading of a WebApp

[lxd]

Web app was build within webapp builder. Currently, it comes up with this error (attached). 

Only one user is having it. I tried on both, Chrome and IE on his PC and it has the same error. It comes up before the app fully loads, so it must gets stuck somewhere with the widgets.

All other users don't have the error. And I can't replicated it. 

This user was ok two weeks ago, so the error is new for him.

There were no changes to the app. Map, that is used by this app, had few new layers added. Web map works fine for him.

Any ideas on further testing?

Anyone else had similar error?

Thanks,

[RobertScheitlin__GISP]

Lidia,

   You have tried to clear the browsers cache right? Have you tried another browser (i.e. Chrome, IE, Firefox)?

[lxd]

Hi Robert,

I have tried both, Chrome and IE. I have tried incognito tab in Chrome (which will assist with not having anything in cache) and the outcome was the same. 

Thanks,