Visual Editor Error In Console

We are having some issue in the Visual Editor to work properly on investigation we noticed an error as below in the browser console. Any idea what could have caused this issue. Due to this issue we are unable to apply any changes on the visual editor.

The specified value "!" does not conform to the required format.  The format is "#rrggbb" where rr, gg, bb are two-digit hexadecimal numbers.
buildFragment @ scripts-ce8f656d5acf6686419700304026d55c1504988612.js?ver=4.2.4:24

Start from checking your custom style in the following directory


Looks like some property was not defined correctly. E.g.

background-color: #!;

sent u an IM for more details