Cannot find the UI element corresponding to this selector from salesforce UI

Help Robot
1

Iam getting error “Cannot find the UI element corresponding to this selector” all of a sudden in production. It worked perfectly until last night and it was in production for months. It just started happening this morning that the scroll bar UI element after logging into salesforce is not found. Please help

2

Does the selector still validate if you try it in Uiexplorer?

3

It does not validate

Thanks,
Murthy

4

If it has been working for months then the only explanation, for me, is that there has been updates/changes in the Salesforce application.