how to fix 'Illegal mix of collations' error

-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.7.4
-- PHP version -- : 7.1.5
-- Browser(s) name and version -- : Chrome 59.0.3071.115

I installed Hikashop Business 3.1.1 this morning.
When I checked database in system/configuration，I found the following error:

Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '='

This error seems to relate to 'User email addresses synchronized'

How to fix this error?

The problem has been solved.

Hello,

Good to know that your problem is solved.
Just in case, if other user got the same kind of problem :
The message in the "check database" is not problematic if your users are already sync. It mostly indicate that it can't perform the verification.
But it also means that you have tables in your database with different collations and you might want to uniformise them.

Regards,