I am trying to migrate a postgresql database to mysql following this tutorial: http://mysqlworkbench.org/2012/11/how-to-migrate-postgresql-databases-to-mysql-using-the-mysql-wo
I encountered the same error. Here is how I solved it:
I downloaded the drivers from https://www.postgresql.org/ftp/odbc/versions/msi/ (Select the most recent one for x64)
In the Overview form, click on the button "Open ODBC Administrator". Add the recently installed "PostgreSQL ANSI(x64)". Click "Finish".
When you "Start Migration", in the source selection form, use "Driver: PostgreSQL ANSI(x64)"