_lookup.html.erb

<%= render 'friends/lookup' %>
<% if @friendships.size > 0 %>
    <table class="table table-striped">
        <thead>
            <tr>
                <th colspan="3" class="page-header">
                    <h2>My Friends</h2>
                </th>
            </tr>
            <tr>
                <th>Name</th>
                <th>Email</th>
                <th>Actions</th>
            </tr>
        <thead>
        <tbody>
            <% @friendships.each do |friend| %>
            <tr>
                <td><%= friend.full_name %></td>
                <td><%= friend.email %></td>
                <td>
                    <%= link_to "View Profile", user_path(friend), class:"btn btn-primary btn-xs" %>
                    <%= link_to 'Remove Friend', friendship_path(friend), :method => :delete, 
                                          :data => {:confirm => "Are you sure?" },
                                          :class => "btn btn-xs btn-danger" %>
                </td>
            </tr>
            <% end %>
        </tbody>
    </table>
<% else %>
    <div class="row col-lg-12">
        <p class="lead"> You don't have any friends yet. Please add some!</p>
    </div>
<% end %>

routes.rb

Rails.application.routes.draw do

  get 'user/registrations'

  devise_for :users, :controllers => {:registrations => "user/registrations"}
  get 'welcome/index'
  resources :user_stocks, except: [:show, :edit, :update]
  resources :users, only: [:show]
  resources :friendships

  # The priority is based upon order of creation: first created -> highest priority.
  # See how all your routes lay out with "rake routes".

  # You can have the root of your site routed with "root"
  #root 'welcome#index'
  root 'welcome#index'
  get 'my_portfolio', to:"users#my_portfolio"
  get 'search_stocks', to: "stocks#search"
  get 'my_friends', to: "users#my_friends"

  # Example of regular route:
  #   get 'products/:id' => 'catalog#view'

  # Example of named route that can be invoked with purchase_url(id: product.id)
  #   get 'products/:id/purchase' => 'catalog#purchase', as: :purchase

  # Example resource route (maps HTTP verbs to controller actions automatically):
  #   resources :products

  # Example resource route with options:
  #   resources :products do
  #     member do
  #       get 'short'
  #       post 'toggle'
  #     end
  #
  #     collection do
  #       get 'sold'
  #     end
  #   end

  # Example resource route with sub-resources:
  #   resources :products do
  #     resources :comments, :sales
  #     resource :seller
  #   end

  # Example resource route with more complex sub-resources:
  #   resources :products do
  #     resources :comments
  #     resources :sales do
  #       get 'recent', on: :collection
  #     end
  #   end

  # Example resource route with concerns:
  #   concern :toggleable do
  #     post 'toggle'
  #   end
  #   resources :posts, concerns: :toggleable
  #   resources :photos, concerns: :toggleable

  # Example resource route within a namespace:
  #   namespace :admin do
  #     # Directs /admin/products/* to Admin::ProductsController
  #     # (app/controllers/admin/products_controller.rb)
  #     resources :products
  #   end
end

users_controller.rb

class UsersController < ApplicationController
  def my_portfolio
    @user_stocks = current_user.stocks
    @user = current_user
  end
  
  def my_friends
    @friendships = current_user.friends
  end 
end

Ok Ryan here it seems like you need to put your file my_friends.html.erb under the users views.

As you are trying to get 'my_friends', to: "users#my_friends" which means rails server is looking for users controller my_friends action (users#my_friends)

Error is still:

ActionView::MissingTemplate in Users#my_friends
Showing /home/ubuntu/ruby-projects/finance-tracker/app/views/users/my_friends.html.erb where line #1 raised:

Missing partial friends/_lookup with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee, :jbuilder]}. Searched in:

• "/home/ubuntu/ruby-projects/finance-tracker/app/views"
• "/usr/local/rvm/gems/ruby-2.3.0/gems/devise-bootstrap-views-0.0.8/app/views"
• "/usr/local/rvm/gems/ruby-2.3.0/gems/twitter-bootstrap-rails-3.2.2/app/views"
• "/usr/local/rvm/gems/ruby-2.3.0/gems/devise-3.5.6/app/views"
  Extracted source (around line #1):
  <%= render 'friends/lookup' %>
  <% if @friendships.size > 0 %>