I get this error
`establish_connection': Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (no such file to load -- active_record/connection_adapters/mysql2_adapter) (RuntimeError)
I had the same error after upgrading from Ubuntu 11.10 to 12.04. This is how I fixed the problem:
gem uninstall mysql2 bundle
I think the key here is the 'native extensions' -- I suppose when I installed last, I was using a different version of mysql.
Installing mysql2 (0.3.11) with native extensions