From: Run Paint Run Run Date: 2011-01-04T07:44:18+09:00 Subject: [ruby-core:34034] Exception#to_s and non-String Messages I don't know when Redmine will be back up, so: Exception objects allow an arbitrary object for the message: >> RUBY_REVISION => 30240 >> FiberError.exception([]).message => [] >> Exception.new(Object.new).message => # And Exception#to_s returns said object verbatim: >> FiberError.exception([]).to_s => [] This breaks the contract of #to_s returning either a String or nil.