When opening a page we get the following error: Unhandled promise rejection string is null checkString@http://localhost:8080/widgets/widgets.js?636776187967671791:11216:13 _processSourceMFCallback@http://localhost:8080/widgets/widgets.js?636776187967671791:11210:41 _hitchArgs/<@http://localhost:8080/mxclientsystem/mxui/mxui.js?636776187967671791:5:26311 a/<@http://localhost:8080/mxclientsystem/mxui/mxui.js?636776187967671791:51:325417 a@http://localhost:8080/mxclientsystem/mxui/mxui.js?636776187967671791:74:183353 M/<@http://localhost:8080/mxclientsystem/mxui/mxui.js?636776187967671791:74:183498 c@http://localhost:8080/mxclientsystem/mxui/mxui.js?636776187967671791:74:181034 Looks like a widget issue, but cannot find out which one. Does anyone has a glue?