After updating Joomla 3.8 this error âUnknown column âa.client_idâ in âwhere clause'â appears when you login into back-end, and there is nothing, it means White Back-end.
There is no Menu, but if you try to select menu (click and drag) then you will see the selected text where it describes its error. It is aÂ database not updated error, but in this situation, you can't go to Extensions and manage the database.
How to Fix Joomla Database Issues:
Login to the Joomla Website Backend.
Copy the below link, replace your domain name withÂ www.YourWebsite.com and load.
If you are in Localhost then change it like thatÂ localhost/YourWebsite/administrator/index.php?option=com_installer&task=database.fix