How to Clear Local Storage Cache

To clear your local storage, please follow the instructions below:

Open Dev Tools: Ctrl+Shift+I, or by right-clicking on the page, and selecting Inspect from the dropdown menu.
Click the arrow located on the right of the pane tabs:

Select Application
Select Clear Storage:
Make sure all options are checked, and then select the Clear site data button.  
You will be automatically logged out of the backend of the site and will need to log back in to see if this has cleared the error you are experiencing.