Question: Following is link to my init script for unicorn.
<https://gist.github.com/1466775>

Restart command has never worked for me. I am using upgrade to restart unicorn after each deploy. But whenever there is major changes like new gems being added, upgrade won't work. Recently, i replaced hoptoad gem with airbrake and it errors out saying 'uninitialized constant Airbrake (NameError)'. But when i stopped and started unicorn again, it worked fine. Does the problem lies in init script or its different problem?

Thanks.

Answer: 
I had a very similar problem and finally [found the solution](http://blog.willj.net/2011/08/02/fixing-the-gemfile-not-found-bundlergemfilenotfound-error/)

I had looked through the logs before but obviously failed to see the `(Bundler::GemfileNotFound)` error. Turns out there are old references to earlier releases and once the gem file changes, the new master silently fails. Tail -f your unicorn log to see what happens. My issues were all fixed as per the link with the following in my unicorn.rb

```
 before_exec do |server|
    ENV['BUNDLE_GEMFILE'] = "#{root}/Gemfile"
 end 

```
I fixed this issue by changing my unicorn init.d script from

```
CMD="cd $APP_ROOT; bundle exec unicorn -D -c $APP_ROOT/config/unicorn.rb -E staging"

```

to this:

```
CMD="cd $APP_ROOT; BUNDLE_GEMFILE=$APP_ROOT/Gemfile bundle exec unicorn -D -c $APP_ROOT/config/unicorn.rb -E staging"

```

Which seems to point to the new bundle gemfile on every new release.
Taking inspiration from [this merge request](https://github.com/sosedoff/capistrano-unicorn/commit/c1e7a3f2794dd070367d0808ad102a6d20d39cf2#diff-14f6e151876ce4733900b16e3c2e8ddb)