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GitHub User: kevinneelands
Don't know if this will help you, but what fixed it for us was specifying a specific version of the devise gem.
in our gemfile:
gem 'devise', '~> 3.0.1'
I'm getting the same error Jonathan E. Emmett is getting. Three other developers, running (virtually) identical systems do NOT get the error. I have tracked it down (I think) to the fact that 'stringify_keys' is getting an array instead of a hash, but why is that happening? I'm running Ruby v. 1.9.3p392 Rails v. 4.0.0.