Error 'SECURITY WARNING: No secret option provided to Rack::Session::Cookie' [duplicate]

Answer 1

This is a known issue under discussion. It is due to the upgrade to Rack 1.4.2 and your choices. Until Rails is updated with a solution, your should ignore the error or downgrade to Rack 1.4.1, according to the people that know ;)

Answer 2

According to the discussion in some other sites, this warning is popping up as Rails is using Rack cookies in a different way than intended. It should be ok to just ignore this warning for now until there is a final agreement on how to handle this issue and a fix in place.