Error installing gems [closed]

Question

I am getting an error when installing certain gems. I am using ubuntu 10.10. The error messages shows this.

ERROR:  While executing gem ... (NoMethodError)
undefined method `spec' for nil:NilClass

Answer 1

I had exactly the same error as this...

While installing Rails 3 my computer suffered a power outage. After restarting the computer and continuing the Rails 3 installation the process failed with this exact same error. The problem was due to the gem install cache which had corrupted / empty gem files. My solution was to clear this cache and run the install again, as follows:

1. Find out the location of your cache using gem env
2. List all the gems in that cache, e.g. ls -l /usr/lib/ruby/gems/1.8/cache/
3. Compare with successfully installed gems using gem list
4. Remove the gems from the cache list that are missing from the gem list e.g. using rm
5. I also had to remove some empty / corrupt gemspec files from the specification directory ls -l /usr/lib/ruby/gems/1.8/specifications/
6. Continue the installation, e.g. sudo gem install -v=3.0.6 rails --no-rdoc --no-ri

Hope this helps someone else who has a power outage or other external failure during a gem install process!