Update Rails 3.1 to Rails 3.2

In Gemfile, change following versions of assets and rails

gem 'rails', '3.2.0'

group :assets do
  gem 'sass-rails', "  ~> 3.2.3"
  gem 'coffee-rails', "~> 3.2.1"
  gem 'uglifier', '>= 1.0.3'
end

Run 'bundle update'

Getting error "File Error: data may have been lost" while using spreadsheet and exporting excel

I am using "Spreadsheet" gem with Rails 2.3.8. Microsoft Office 2007 is installed on my system.
I successfully fitted the code snippets in one of my controller.
I just wrote the code to create Worksheet and pushed one row record in it.
Number of records pushed in that row is around 330.
When I export the spreadsheet/excel, I got following error:

"File Error: data may have been lost"

Clicked on Ok and it created the excel file with the File Type "Microsoft Office Excel 97-2003 Worksheet" with one sheet having 1 row.
When closely analyzed the sheet, I found that Number of maximum columns that can be in that sheet is only 256 and as I was trying to have around 330 columns hence I was getting the error.