Error in activeadmin gem - ruby-on-rails-4

Question

hello I am here again with an error in my project.
I want to install activeadmin gem but it is showing me error as below.my rails version is 4.0.0
I looked to the solution provided but then also it shows me error.
Updating git://github.com/gregbell/active_admin.git
fatal: ambiguous argument 'rails4': unknown revision or path not in the working
tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Git error: command `git rev-parse rails4` in directory
C:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/cache/bundler/git/active_admin-d
67faab65e9b74efbc8efb4a777a851e9f78b2ca has failed.
If this error persists you could try removing the cache directory
'C:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/cache/bundler/git/active_admin-
d67faab65e9b74efbc8efb4a777a851e9f78b2ca'
If I remove the branch name it shows me error
Updating git://github.com/gregbell/active_admin.git
Resolving dependencies...
Bundler could not find compatible versions for gem "devise":
In Gemfile:
activeadmin (>= 0) x86-mingw32 depends on
devise (~> 3.2) x86-mingw32
devise (3.1.1)

Answer 1

Just you need to bundle first in starting of app.
No need to enter other gem files.
gem 'activeadmin', github: 'gregbell/active_admin'
in the Gemfile and bundle .It will automatically download all necessary gem in your application.
C:\Sites\try>bundle
Updating git://github.com/gregbell/active_admin.git
Fetching gem metadata from https://rubygems.org/...........
Fetching gem metadata from https://rubygems.org/..
Resolving dependencies...
Using rake (10.1.1)
Using i18n (0.6.9)
Using minitest (4.7.5)
Using multi_json (1.8.4)
Using atomic (1.1.14)
Using thread_safe (0.1.3)
Using tzinfo (0.3.38)
Using activesupport (4.0.0)
Using builder (3.1.4)
Using erubis (2.7.0)
Using rack (1.5.2)
Using rack-test (0.6.2)
Using actionpack (4.0.0)
Using mime-types (1.25.1)
Using polyglot (0.3.3)
Using treetop (1.4.15)
Using mail (2.5.4)
Using actionmailer (4.0.0)
Installing arbre (1.0.1)
Using sass (3.2.14)
Using thor (0.18.1)
Installing bourbon (3.1.8)
Using coffee-script-source (1.6.3)
Using execjs (2.0.2)
Using coffee-script (2.2.0)
Using railties (4.0.0)
Using coffee-rails (4.0.1)
Using bcrypt-ruby (3.1.2)
Installing orm_adapter (0.5.0)
Using warden (1.2.3)
Installing devise (3.2.2)
Installing formtastic (2.3.0.rc2)
Installing has_scope (0.6.0.rc)
Installing responders (1.0.0)
Installing inherited_resources (1.4.1)
Using jquery-rails (3.0.4)
Using jquery-ui-rails (4.1.1)
Installing kaminari (0.15.1)
Using activemodel (4.0.0)
Using activerecord-deprecated_finders (1.0.3)
Using arel (4.0.1)
Using activerecord (4.0.0)
Using bundler (1.3.5)
Using hike (1.2.3)
Using tilt (1.4.1)
Using sprockets (2.10.1)
Using sprockets-rails (2.0.1)
Using rails (4.0.0)
Installing polyamorous (0.6.4)
Installing ransack (1.1.0)
Using sass-rails (4.0.1)
Using activeadmin (1.0.0.pre) from git://github.com/gregbell/active_admin.git (at master)
Using jbuilder (1.5.3)
Using json (1.8.1)
Using pg (0.17.0)
Using rdoc (4.1.1)
Using sdoc (0.4.0)
Using turbolinks (2.2.0)
Using uglifier (2.4.0)
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.

Answer 2

I suspect that your Gemfile restricts your devise version to something like ~> 3.1.0, which means it won't let you upgrade to 3.2. You are correct in removing the rails4 branch, as master is now the official Rails4-compatible branch. If you remove your devise version restriction, you should probably be able to get it working.

Answer 3

Just for information:
If someone faces similar issue, and already have gem 'devise', without version in the Gemfile, then first do a bundle install and then try to update Gemfile with active_admin