updating rails version to 3.1.3 get error

hi all,
i have ruby : 1.8.7 rails :2.3.11 and rubygem:1.6.2 installed on my Windows sys. my application work without error .I have upgraded the environment
to gem:1.8.12,rails:3.1.3 ,ruby:1.9.2
i have getting the following error on starting the Webrick server

D:/Hemant/Suggestica_setup/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in require': cannot load such file -- initializer (LoadError) from D:/Hemant/Suggestica_setup/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in require’
from C:/Documents and Settings/ct013/My Documents/Aptana RadRails Workspace/Suggestica_Admin/config/boot.rb:55:in load_initializer' from C:/Documents and Settings/ct013/My Documents/Aptana RadRails Workspace/Suggestica_Admin/config/boot.rb:38:in run’
from C:/Documents and Settings/ct013/My Documents/Aptana RadRails Workspace/Suggestica_Admin/config/boot.rb:11:in boot!' from C:/Documents and Settings/ct013/My Documents/Aptana RadRails Workspace/Suggestica_Admin/config/boot.rb:114:in <top (required)>’
from D:/Hemant/Suggestica_setup/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in require' from D:/Hemant/Suggestica_setup/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in require’
from script/server:2:in <top (required)>' from -e:2:in load’
from -e:2:in `’

can anyone know why this exception coming ?

hi all,
i have ruby : 1.8.7 rails :2.3.11 and rubygem:1.6.2 installed on my
Windows sys. my application work without error .I have upgraded the
environment
to gem:1.8.12,rails:3.1.3 ,ruby:1.9.2
i have getting the following error on starting the Webrick server

Did you google to find how to upgrade an app to rails 3, you need to
make changes to the app itself?

If you create a new app using rails 3 is it ok?

Colin