I'm in the process of upgrading from 11.1.0. to 12cR3.
I download all the agents required and plugins to a particular directory and clicked valid.The agents got recognized,but plug-ings didn't.
I didn't unzip the agents and plugins.
Do I need to unizip the plugins for them to be recoginzed.
To confirm you picked up the pre-upgrade console patch that go released in June end and all the right plugin from the OTN page - http://www.oracle.com/technetwork/oem/grid-control/downloads/oem-upgrade-console-502238.html
When you provide the location in the manage software page and click validate - do you see any changes in the graph ? any error ?
Can you log an SR for this issue.
There is indeed a MySQL plugin provided by Pythian, but it is not distributed as a component of the base EM12c product. Please see the EM12c Extensibility Exchange (http://apex.oracle.com/pls/apex/f?p=34841:11) to find that plugin and more, or see Pythian's page for the plugin at http://www.pythian.com/blog/mysql-plugin-for-oracle-enterprise-manager/.