I am starting to use MySQL Workbench tool especially for data modeling. So, the first I would like to do is reverse engineering of my existing database on web server. But I
Wow, i just go to C:\xampp\mysql\bin and run mysql_upgrade.exe
It repair itself and now everithing is working great.
I'm using MySQL trough MAMP Pro, and Kevin's answer didn't work for me. Yes, I had to do a mysql upgrade BUT I had to use the following commands on the Terminal:
/Applications/MAMP/bin/repairMysql.sh
/Applications/MAMP/bin/upgradeMysql.sh
This worked for me. Hope this can be helpful to somebody else..
On windows, with XAMPP i managed to fix the issue by going to the directory:
C:\xampp\mysql\bin
and running the executable mysql_upgrade.exe
you'll find inside, make sure your mysql server is running.
If this happens on a specific query, be aware that this can also happen when you try to use an undefined function.