Traffic Graph Error after 2.1.3 -> 2.1.4

[JWU42]

I get the following displayed:

error on line 39 at column 1: Input is not proper UTF-8, indicate encoding !
Bytes: 0x00 0x28 0x27 0x67

[jimp]

Which traffic graph?

Have you cleared your browser cache?

[JWU42]

@jimp,

Apologies for delay - thought I had notify turned on…

Cache is cleared.

This appears on the dashboard traffic graph widget.  It will also appear on Stauts - Traffic Graph but not initially (i.e., the graph will work fine for a period of time).  This does NOT happen on the dashboard as it has not been functional at all since the upgrade.

Hope that helps.

Using Chrome-Dev FWIW...