Rails errors using whenever

Hi I've migrated from Rails 3.2.12 to finally 4.2.0

now I got this erros while using whenever for scheduling cronjobs

from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler.rb:122:in `setup'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/setup.rb:18:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /usr/local/rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/spec_set.rb:92:in `block in materialize': Could not find minitest-5.2.0 in any of the sources (Bundler::GemNotFound)
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/spec_set.rb:85:in `map!'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/spec_set.rb:85:in `materialize'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/definition.rb:132:in `specs'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/definition.rb:177:in `specs_for'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/definition.rb:166:in `requested_specs'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/environment.rb:18:in `requested_specs'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/runtime.rb:13:in `setup'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler.rb:122:in `setup'
from /usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/setup.rb:18:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /usr/local/rvm/rubies/ruby-2.0.0-p643/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p643/gems/bundler-1.9.4/lib/bundler/spec_set.rb:92:in `block in materialize': Could not find minitest-5.2.0 in any of the sources (Bundler::GemNotFound)

How can I fix this?