diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index d34a9c0ae..864a9d094 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -964,7 +964,7 @@ module ApplicationHelper
                 link = link_to_project(p, {:only_path => only_path}, :class => 'project')
               end
             when 'user'
-              u = User.visible.where(:id => oid, :type => 'User').first
+              u = User.visible.find_by(:id => oid, :type => 'User')
               link = link_to_user(u, :only_path => only_path) if u
             end
           elsif sep == ':'
@@ -1025,12 +1025,12 @@ module ApplicationHelper
                 link = link_to_project(p, {:only_path => only_path}, :class => 'project')
               end
             when 'user'
-              u = User.visible.where("LOWER(login) = :s AND type = 'User'", :s => name.downcase).first
+              u = User.visible.find_by("LOWER(login) = :s AND type = 'User'", :s => name.downcase)
               link = link_to_user(u, :only_path => only_path) if u
             end
           elsif sep == "@"
             name = remove_double_quotes(identifier)
-            u = User.visible.where("LOWER(login) = :s AND type = 'User'", :s => name.downcase).first
+            u = User.visible.find_by("LOWER(login) = :s AND type = 'User'", :s => name.downcase)
             link = link_to_user(u, :only_path => only_path) if u
           end
         end
diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index 6795f602e..cc9b5f930 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -276,7 +276,7 @@ class Attachment < ActiveRecord::Base
   def self.find_by_token(token)
     if token.to_s =~ /^(\d+)\.([0-9a-f]+)$/
       attachment_id, attachment_digest = $1, $2
-      attachment = Attachment.where(:id => attachment_id, :digest => attachment_digest).first
+      attachment = Attachment.find_by(:id => attachment_id, :digest => attachment_digest)
       if attachment && attachment.container.nil?
         attachment
       end
diff --git a/app/models/principal.rb b/app/models/principal.rb
index aac4e6b0d..08926d3a1 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -132,7 +132,7 @@ class Principal < ActiveRecord::Base
   end
 
   def visible?(user=User.current)
-    Principal.visible(user).where(:id => id).first == self
+    Principal.visible(user).find_by(:id => id) == self
   end
 
   # Returns true if the principal is a member of project
diff --git a/app/models/repository.rb b/app/models/repository.rb
index 235739057..256222f50 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -247,7 +247,7 @@ class Repository < ActiveRecord::Base
     return nil if name.blank?
     s = name.to_s
     if s.match(/^\d*$/)
-      changesets.where("revision = ?", s).first
+      changesets.find_by(:revision => s)
     else
       changesets.where("revision LIKE ?", s + '%').first
     end
diff --git a/app/models/repository/git.rb b/app/models/repository/git.rb
index 4cb16e524..e48d36490 100644
--- a/app/models/repository/git.rb
+++ b/app/models/repository/git.rb
@@ -45,7 +45,7 @@ class Repository::Git < Repository
     return false if v.nil?
     v.to_s != '0'
   end
- 
+
   def report_last_commit=(arg)
     merge_extra_info "extra_report_last_commit" => arg
   end
@@ -89,7 +89,7 @@ class Repository::Git < Repository
 
   def find_changeset_by_name(name)
     if name.present?
-      changesets.where(:revision => name.to_s).first ||
+      changesets.find_by(:revision => name.to_s) ||
         changesets.where('scmid LIKE ?', "#{name}%").first
     end
   end
diff --git a/app/models/repository/mercurial.rb b/app/models/repository/mercurial.rb
index 922893a6a..2a8079ca0 100644
--- a/app/models/repository/mercurial.rb
+++ b/app/models/repository/mercurial.rb
@@ -99,7 +99,7 @@ class Repository::Mercurial < Repository
     if /[^\d]/ =~ s or s.size > 8
       cs = changesets.where(:scmid => s).first
     else
-      cs = changesets.where(:revision => s).first
+      cs = changesets.find_by(:revision => s)
     end
     return cs if cs
     changesets.where('scmid LIKE ?', "#{s}%").first
diff --git a/app/models/role.rb b/app/models/role.rb
index bf987e210..36ef4bc8b 100644
--- a/app/models/role.rb
+++ b/app/models/role.rb
@@ -293,7 +293,7 @@ private
   end
 
   def self.find_or_create_system_role(builtin, name)
-    role = unscoped.where(:builtin => builtin).first
+    role = unscoped.find_by(:builtin => builtin)
     if role.nil?
       role = unscoped.create(:name => name) do |r|
         r.builtin = builtin
diff --git a/app/models/token.rb b/app/models/token.rb
index 5990056f5..85d6abb9a 100644
--- a/app/models/token.rb
+++ b/app/models/token.rb
@@ -112,7 +112,7 @@ class Token < ActiveRecord::Base
     key = key.to_s
     return nil unless action.present? && key =~ /\A[a-z0-9]+\z/i
 
-    token = Token.where(:action => action, :value => key).first
+    token = Token.find_by(:action => action, :value => key)
     if token && (token.action == action) && (token.value == key) && token.user
       if validity_days.nil? || (token.created_on > validity_days.days.ago)
         token
diff --git a/app/models/user.rb b/app/models/user.rb
index 23d897649..c5061225c 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -492,7 +492,7 @@ class User < Principal
       user = where(:login => login).detect {|u| u.login == login}
       unless user
         # Fail over to case-insensitive if none was found
-        user = where("LOWER(login) = ?", login.downcase).first
+        user = find_by("LOWER(login) = ?", login.downcase)
       end
       user
     end
@@ -610,24 +610,24 @@ class User < Principal
     # eg. project.children.visible(user)
     Project.unscoped do
       return @project_ids_by_role if @project_ids_by_role
-  
+
       group_class = anonymous? ? GroupAnonymous : GroupNonMember
       group_id = group_class.pluck(:id).first
-  
+
       members = Member.joins(:project, :member_roles).
         where("#{Project.table_name}.status <> 9").
         where("#{Member.table_name}.user_id = ? OR (#{Project.table_name}.is_public = ? AND #{Member.table_name}.user_id = ?)", self.id, true, group_id).
         pluck(:user_id, :role_id, :project_id)
-  
+
       hash = {}
       members.each do |user_id, role_id, project_id|
         # Ignore the roles of the builtin group if the user is a member of the project
         next if user_id != id && project_ids.include?(project_id)
-  
+
         hash[role_id] ||= []
         hash[role_id] << project_id
       end
-  
+
       result = Hash.new([])
       if hash.present?
         roles = Role.where(:id => hash.keys).to_a
@@ -798,7 +798,7 @@ class User < Principal
   # Returns the anonymous user.  If the anonymous user does not exist, it is created.  There can be only
   # one anonymous user per database.
   def self.anonymous
-    anonymous_user = AnonymousUser.unscoped.first
+    anonymous_user = AnonymousUser.unscoped.find_by(:lastname => 'Anonymous')
     if anonymous_user.nil?
       anonymous_user = AnonymousUser.unscoped.create(:lastname => 'Anonymous', :firstname => '', :login => '', :status => 0)
       raise 'Unable to create the anonymous user.' if anonymous_user.new_record?
diff --git a/app/models/wiki.rb b/app/models/wiki.rb
index 683fa24f3..186abdc74 100644
--- a/app/models/wiki.rb
+++ b/app/models/wiki.rb
@@ -53,7 +53,7 @@ class Wiki < ActiveRecord::Base
     @page_found_with_redirect = false
     title = start_page if title.blank?
     title = Wiki.titleize(title)
-    page = pages.where("LOWER(title) = LOWER(?)", title).first
+    page = pages.find_by("LOWER(title) = LOWER(?)", title)
     if page.nil? && options[:with_redirect] != false
       # search for a redirect
       redirect = redirects.where("LOWER(title) = LOWER(?)", title).first
diff --git a/lib/redmine/field_format.rb b/lib/redmine/field_format.rb
index c4960c0f7..4d168b434 100644
--- a/lib/redmine/field_format.rb
+++ b/lib/redmine/field_format.rb
@@ -155,7 +155,7 @@ module Redmine
       def target_class
         nil
       end
- 
+
       def possible_custom_value_options(custom_value)
         possible_values_options(custom_value.custom_field, custom_value.customized)
       end
@@ -625,7 +625,7 @@ module Redmine
           value ||= label
           checked = (custom_value.value.is_a?(Array) && custom_value.value.include?(value)) || custom_value.value.to_s == value
           tag = view.send(tag_method, tag_name, value, checked, :id => nil)
-          s << view.content_tag('label', tag + ' ' + label) 
+          s << view.content_tag('label', tag + ' ' + label)
         end
         if custom_value.custom_field.multiple?
           s << view.hidden_field_tag(tag_name, '', :id => nil)
@@ -730,7 +730,7 @@ module Redmine
       def reset_target_class
         @target_class = nil
       end
- 
+
       def possible_custom_value_options(custom_value)
         options = possible_values_options(custom_value.custom_field, custom_value.customized)
         missing = [custom_value.value_was].flatten.reject(&:blank?) - options.map(&:last)
@@ -776,7 +776,7 @@ module Redmine
     class EnumerationFormat < RecordList
       add 'enumeration'
       self.form_partial = 'custom_fields/formats/enumeration'
- 
+
       def label
         "label_field_format_enumeration"
       end
@@ -964,7 +964,7 @@ module Redmine
           end
         else
           if custom_value.value.present?
-            attachment = Attachment.where(:id => custom_value.value.to_s).first
+            attachment = Attachment.find_by(:id => custom_value.value.to_s)
             extensions = custom_value.custom_field.extensions_allowed
             if attachment && extensions.present? && !attachment.extension_in?(extensions)
               errors << "#{::I18n.t('activerecord.errors.messages.invalid')} (#{l(:setting_attachment_extensions_allowed)}: #{extensions})"
@@ -978,14 +978,14 @@ module Redmine
       def after_save_custom_value(custom_field, custom_value)
         if custom_value.saved_change_to_value?
           if custom_value.value.present?
-            attachment = Attachment.where(:id => custom_value.value.to_s).first
+            attachment = Attachment.find_by(:id => custom_value.value.to_s)
             if attachment
               attachment.container = custom_value
               attachment.save!
             end
           end
           if custom_value.value_before_last_save.present?
-            attachment = Attachment.where(:id => custom_value.value_before_last_save.to_s).first
+            attachment = Attachment.find_by(:id => custom_value.value_before_last_save.to_s)
             if attachment
               attachment.destroy
             end
diff --git a/lib/tasks/migrate_from_trac.rake b/lib/tasks/migrate_from_trac.rake
index 2b8eeea89..eb0d81e0a 100644
--- a/lib/tasks/migrate_from_trac.rake
+++ b/lib/tasks/migrate_from_trac.rake
@@ -453,7 +453,7 @@ namespace :redmine do
         puts
 
         # Trac 'resolution' field as a Redmine custom field
-        r = IssueCustomField.where(:name => "Resolution").first
+        r = IssueCustomField.find_by(:name => "Resolution")
         r = IssueCustomField.new(:name => 'Resolution',
                                  :field_format => 'list',
                                  :is_filter => true) if r.nil?