使用Rails 3，从Mongoid 2.x升级到Mongoid 3.X后，我的Heroku + MongoHQ设置停止工作。 有趣的是，我的开发和测试框架和我的整个测试套件通过就好了。
我怀疑，问题是我mongoid.yml文件，但我已经尝试搜索文档，谷歌和计算器，以及使用的所有建议的格式，包括此： Heroku的mongohq和mongoid蒙戈:: ConnectionFailure或实际这样的： HTTPS：/ /gist.github.com/2900804
修订版7月16日：这是我mongoid.yml文件的样子，想多事情后 + 贾森什么从MongoHQ建议后：
development:
sessions:
default:
database: development
hosts:
- localhost:27017
test:
sessions:
default:
database: test
hosts:
- localhost:27017
production:
sessions:
default:
uri: <%= ENV['MONGOHQ_URL'] %>
options:
skip_version_check: true
safe: true
（我的理解，它本质上是一样的一个在上面的链接，但它使用URI;我试过其他办法，分割MONGOHQ_URL成单独的字段，以及，但它并没有帮助）
我试过设置mongoid为3.0.0rc和离开版本空白在我的Gemfile。 使用失败，原因是HTTPS证书什么的GitHub的版本，所以我没有理会多次尝试它。
什么动作控制器说这是：
Moped::Errors::OperationFailure in Home#index
Showing /app/app/views/home/index.html.haml where line #2 raised:
The operation: #<Moped::Protocol::Command
@length=68
@request_id=4
@response_to=0
@op_code=2004
@flags=[:slave_ok]
@full_collection_name=".$cmd"
@skip=0
@limit=-1
@selector={:count=>:posts, :query=>{}}
@fields=nil>
failed with error "db assertion failure"
当我运行
heroku run console
..我得到这个：
irb(main):052:0> Location.create!
NoMethodError: undefined method `[]' for nil:NilClass
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:74:in `block in command'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:522:in `[]'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:522:in `block (3 levels) in flush'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:521:in `map'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:521:in `block (2 levels) in flush'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:113:in `ensure_connected'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:517:in `block in flush'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:532:in `logging'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:516:in `flush'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:505:in `process'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:70:in `command'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/node.rb:356:in `refresh'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/cluster.rb:101:in `block in refresh'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/cluster.rb:114:in `each'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/cluster.rb:114:in `refresh'
from /app/vendor/bundle/ruby/1.9.1/gems/moped-1.1.1/lib/moped/cluster.rb:67:in `nodes'
... 15 levels...
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:405:in `__run_callback'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:385:in `_run_save_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.6/lib/active_support/callbacks.rb:81:in `run_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/callbacks.rb:98:in `run_callbacks'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/persistence/insertion.rb:23:in `prepare'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/persistence/operations/insert.rb:26:in `persist'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/persistence.rb:50:in `insert'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/persistence.rb:251:in `block in create!'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/threaded/lifecycle.rb:173:in `_creating'
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.1/lib/mongoid/persistence.rb:249:in `create!'
from (irb):52
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands/console.rb:47:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands/console.rb:8:in `start'
from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.6/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'irb(main):053:0>
我想我GOOGLE了一切，通过多个github上mongoid问题跑，多次读取的文档......和我在这里运行的想法。
什么浮现在脑海中，我应该尝试下？
更新7月16日：这是当我混帐推Heroku的主（做什么杰森从MongoHQ建议后）的Heroku这样说：
git push heroku master
Counting objects: 7, done.
Delta compression using up to 16 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), 372 bytes, done.
Total 4 (delta 3), reused 0 (delta 0)
-----> Heroku receiving push
-----> Ruby/Rails app detected
-----> Installing dependencies using Bundler version 1.2.0.pre
Running: bundle install --without development:test --path vendor/bundle --binstubs bin/ --deployment
Using rake (0.9.2.2)
Using i18n (0.6.0)
Using multi_json (1.3.6)
Using activesupport (3.2.6)
Using builder (3.0.0)
# ... shortened this #
Using libv8 (3.3.10.4)
Using moped (1.1.2)
Using origin (1.0.4)
Using mongoid (3.0.0.rc)
Using omniauth (1.1.0)
Using quimby (0.4.5)
Using bundler (1.2.0.pre)
Using rails (3.2.6)
Using therubyracer (0.10.1)
Using thin (1.3.1)
Your bundle is complete! It was installed into ./vendor/bundle
Cleaning up the bundler cache.
-----> Writing config/database.yml to read from DATABASE_URL
-----> Preparing app for Rails asset pipeline
Running: rake assets:precompile
Asset precompilation completed (31.24s)
-----> Rails plugin injection
Injecting rails_log_stdout
Injecting rails3_serve_static_assets
-----> Discovering process types
Procfile declares types -> (none)
Default types for Ruby/Rails -> console, rake, web, worker
-----> Compiled slug size is 18.7MB
-----> Launching... done, v92
http://xxxxx.herokuapp.com deployed to Heroku
To git@heroku.com:xxxxx.git
b2d97xy..7b0aczy master -> master
更新2 7月16日：做了杰森＆MrKurt说（第一忘了运行包更新mongoid，但这并没有帮助）。 现在的错误改变，但：
NoMethodError in Home#index
Showing /app/app/views/home/index.html.haml where line #2 raised:
undefined method `[]' for nil:NilClass
Extracted source (around line #2):
1: %h1 Most recent posts
2: - if @posts.length > 0
