Gem.Source_Index Is Deprecated, Use Specification. Should I Re-Install Gem or Rails

How to handle deprecated gem warning (SourceIndex#all_gems)?

I got the same errors for a bunch of my gems in a non-Rails environment when I upgraded to rubygems 1.8.0. I got the warnings any time rubygems is required. Looking around the 'Net, it seems like it might be a problem also with rubygems 1.7.x, but I never had one of those versions installed so I'm not sure. I fixed this by running:

gem pristine --all --no-extensions

I had to run it a few times - it kept erroring out (but usually not in the same place from run to run). Eventually it got far enough that it had addressed the majority of my gems.

There were a few gems that didn't get their specifications regenerated correctly (json and sequel, specifically in my case) because they needed to build an extension. (The gem command output indicated it was skipping them, though it was easy to miss that message amidst all the deprecation warnings.) For those gems, I uninstalled them and then reinstalled them again (they'd previously been installed by bundler in rubygems 1.5.x) and that fixed the remaining warnings. It may be that I could have started with that plan of attack originally, but I didn't try.

Getting an error when trying to run rake db:migrate

Check what versions of rails you have installed:

$ gem list rails

*** LOCAL GEMS ***

rails (3.2.3, 2.3.14)

You should have multiple of them like I do here 3.2.3 and 2.3.14

afterwards uninstall the ones you dont need with:

$ gem uninstall rails -v2.3.14
Remove executables:
    rails

in addition to the gem? [Yn]  Y
Removing rails
Successfully uninstalled rails-2.3.14

at the end you should have just one version of rails:

$ gem list rails

*** LOCAL GEMS ***

rails (3.2.3)

Rails is Nuked - How to Reinstall

The difficulty here is likely bundler doesn't realize all these gems are gone. Try going into your Rails directory and doing 'bundle install'; this should result in all your gems returning.

Why would an app run fine in the system environment, but not under RVM?

Yes, RubyGems has had a very fast development pace lately and is not completely backwards compatible. Try:

gem install rubygems -v 1.3.7

You may have to clear out the gemset to reinstall rubygems...

If you're using rvm, you can change the version of RubyGems with the following command:

rvm rubygems 1.3.7

Error while running an rails application from command prompt

As the error message says:

For information about OpenSSL certificates, see bit.ly/ruby-ssl.

bit.ly/ruby-ssl points to http://railsapps.github.io/openssl-certificate-verify-failed.html which has the explanation for what is happening, and suggestions on how to fix it.

Changing https to http in source 'http://rubygems.org' is one of the recommended workarounds.

There is a windows specific solution at the bottom which recommends downloading a cacert.pem for RailsInstaller