"NoMethodError: undefined method `each' for nil:NilClass"

[sanjeev29]

Getting below error for all steps that include 'rake' and also while running 'ruby app.rb'

rake aborted!
NoMethodError: undefined method each' for nil:NilClass /edx/app/forum/.gem/ruby/2.5.0/gems/mongo-2.5.3/lib/mongo/cluster.rb:192:in initialize'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongo-2.5.3/lib/mongo/client.rb:454:in new' /edx/app/forum/.gem/ruby/2.5.0/gems/mongo-2.5.3/lib/mongo/client.rb:454:in create_from_addresses'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongo-2.5.3/lib/mongo/client.rb:253:in initialize' /edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients/factory.rb:64:in new'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients/factory.rb:64:in create_client' /edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients/factory.rb:27:in create'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients.rb:69:in block in with_name' /edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients.rb:68:in synchronize'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients.rb:68:in with_name' /edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/persistence_context.rb:114:in client'
/edx/app/forum/.gem/ruby/2.5.0/gems/mongoid-7.0.5/lib/mongoid/clients/options.rb:78:in mongo_client' /home/sanjeev/edx/cs_comments_service/app.rb:172:in <top (required)>'
/edx/app/forum/.gem/ruby/2.5.0/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in require' /edx/app/forum/.gem/ruby/2.5.0/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in block in require'
/edx/app/forum/.gem/ruby/2.5.0/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:291:in load_dependency' /edx/app/forum/.gem/ruby/2.5.0/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in require'
/home/sanjeev/edx/cs_comments_service/Rakefile:24:in block in <top (required)>' /edx/app/forum/.gem/ruby/2.5.0/gems/rake-12.0.0/exe/rake:27:in <top (required)>'
Tasks: TOP => search:initialize => environment

[M0M0K4S4N]

Also me on rebuild_index
https://pastebin.com/QcTqKKA0

rake aborted!
NoMethodError: undefined method `each' for nil:NilClass
...
...
Tasks: TOP => search:rebuild_index => environment

---

@sanjeev29
Solution found for me.
Try to set environment variable "MONGOHQ_URL" to your mongodb server connection url.

Related configuration is mongoid.yml so there is no default value for MONGOHQ_URL.