Error in Migration

I am a RoR newbie. I am getting this error when trying to migrate my 2.x
project to 3.x project.

`normalize_path': undefined method `to_sym' for nil:NilClass

In that line i can see the following code

why $1.to_sym ends with NilClass error

That means that $1 is nil. Does the stack trace show which line of
your application code is causing the problem? What are you doing when
you get the error? Post the full stack trace if you can't see what
the problem is.

Did you google for how to upgrade an app to Rails 3, it is not the
easiest thing for a beginner to do?