Resolution:
Under your CStore Essentials Web Account,
Go to Day Closing > Settings > Categories/Departments:
Make sure that none of the Category or Department 'Name' contains any invalid 'Special Character' or 'prefix/suffix by blank space'.
Remove the 'Special Character' if you find any, and you should not get the Error any more.
Special Characters to avoid,
( Name ) prefix or suffix with unwanted Blank Space
Comma ( , )
Apostrophe / Single quote ( ' )
Question mark ( ? )
At symbol ( @ )
Ampersand ( & )
Exclamation point ( ! )
Number/pound sign ( # )
Tilde ( ~ )
Asterisk ( * )
Underscore ( _ )
Semi-colon ( ; )
Colon ( : )
Plus sign ( + )
etc...