diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1eaaf0a9..9b70f3c6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,9 +2,9 @@
 
 ## Unreleased
 - Use jQuery 2.x - 2.2.4
-  - If there are `//= require jquery` clauses in the main application, replace them with `//= require jquery2`
+  - **If there are `//= require jquery` clauses in the main application, replace them with `//= require jquery2`**
 - Add Ruby 3.3 and Rails 7.2 to CI
-- Replace Tuzitio links with `camaleon.website` and http with https
+- Replace Tuzitio links with `camaleon.website` and `http` with `https`
 - On cama_site_check_existence, if site is unknown, use `allow_other_host: true` for redirection to main site
   - Starting from Rails 7.0 a redirection to other host will raise an exception unless the `redirect_to` method is 
     called with the `allow_other_host: true` option
@@ -12,6 +12,10 @@
 - Use MiniMime for mime types, because the MiniMagick 5.0 has no Image#mime_type
 - Reimplement the temporary uploaded file removing, wrapping it in a bl…ock to make possible overriding the block in the app initializer to use an async job
 - Sanitize name and description attrs of TermTaxonomy classes to prevent XSS attacks
+- **Potentially breaking change:** Fix ActiveRecord deprecations from Rails 6.1
+  - `fields`, `field_values`, and `field_groups` associations have been removed from the CustomFieldsRead mixin module
+  - `custom_fields`, `custom_field_values`, and `custom_field_groups` associations should be used instead
+  - Beware that the CustomFieldsRead mixin is included into the TermTaxonomy base model, PostDefault model, and UserMethods mixin
 
 ## [2.7.5](https://github.com/owen2345/camaleon-cms/tree/2.7.5) (2023-11-22)
 - Fix the test email for non-main sites by [brian-kephart](https://github.com/brian-kephart) in [\#1050](https://github.com/owen2345/camaleon-cms/pull/1050)
diff --git a/app/models/camaleon_cms/custom_field_group.rb b/app/models/camaleon_cms/custom_field_group.rb
index f58f236b..141b57a1 100644
--- a/app/models/camaleon_cms/custom_field_group.rb
+++ b/app/models/camaleon_cms/custom_field_group.rb
@@ -5,8 +5,8 @@ class CustomFieldGroup < CamaleonCms::CustomField
     alias_attribute :site_id, :parent_id
 
     default_scope do
-      where.not(object_class: '_fields')
-           .reorder("#{CamaleonCms::CustomField.table_name}.field_order ASC")
+      where("object_class != '_fields'")
+        .reorder("#{CamaleonCms::CustomField.table_name}.field_order ASC")
     end
 
     has_many :metas, -> { where(object_class: 'CustomFieldGroup') }, foreign_key: :objectid, dependent: :destroy
diff --git a/app/models/camaleon_cms/post_default.rb b/app/models/camaleon_cms/post_default.rb
index 89e877b5..44536119 100644
--- a/app/models/camaleon_cms/post_default.rb
+++ b/app/models/camaleon_cms/post_default.rb
@@ -42,7 +42,7 @@ def self.find_by_slug(slug)
       res = where("#{CamaleonCms::Post.table_name}.slug = ? OR #{CamaleonCms::Post.table_name}.slug LIKE ? ", slug,
                   "%-->#{slug}<!--%")
       # end
-      res.reorder('').first
+      res.take
     end
 
     # return the parent of a post (support for sub contents or tree of posts)
diff --git a/app/models/concerns/camaleon_cms/custom_fields_read.rb b/app/models/concerns/camaleon_cms/custom_fields_read.rb
index 53362364..3111eb14 100644
--- a/app/models/concerns/camaleon_cms/custom_fields_read.rb
+++ b/app/models/concerns/camaleon_cms/custom_fields_read.rb
@@ -3,18 +3,6 @@ module CustomFieldsRead
     extend ActiveSupport::Concern
     included do
       before_destroy :_destroy_custom_field_groups
-      # DEPRECATED, INSTEAD USE: custom_fields
-      has_many :fields, lambda { |object|
-                          where(object_class: object.class.to_s.gsub('Decorator', '').gsub('CamaleonCms::', ''))
-                        }, class_name: 'CamaleonCms::CustomField', foreign_key: :objectid
-      # DEPRECATED, INSTEAD USE: custom_field_values
-      has_many :field_values, lambda { |object|
-                                where(object_class: object.class.to_s.gsub('Decorator', '').gsub('CamaleonCms::', ''))
-                              }, class_name: 'CamaleonCms::CustomFieldsRelationship', foreign_key: :objectid, dependent: :delete_all
-      # DEPRECATED, INSTEAD USE: custom_field_groups
-      has_many :field_groups, lambda { |object|
-                                where(object_class: object.class.to_s.parseCamaClass)
-                              }, class_name: 'CamaleonCms::CustomFieldGroup', foreign_key: :objectid
     end
 
     # get custom field groups for current object
@@ -38,7 +26,7 @@ def get_field_groups(args = {})
                { kind: args,
                  include_parent: false }
              else
-               { kind: 'Post', include_parent: false }.merge(args)
+               { kind: 'Post', include_parent: false }.merge!(args)
              end
       class_name = self.class.to_s.parseCamaClass
       case class_name
@@ -73,7 +61,7 @@ def get_field_groups(args = {})
           CamaleonCms::CustomFieldGroup.where(object_class: "PostType_#{args[:kind]}", objectid: id)
         end
       else # 'Plugin' or other classes
-        field_groups
+        custom_field_groups
       end
     end
 
@@ -196,8 +184,8 @@ def get_fields_object(_f = true)
     # kind: argument only for PostType model: (Post | Category | PostTag), default => Post. If kind = "" this will add group for all post_types
     def add_custom_field_group(values, kind = 'Post')
       values = values.with_indifferent_access
-      group = get_field_groups(kind).where(slug: values[:slug]).first
-      unless group.present?
+      group = get_field_groups(kind).find_by(slug: values[:slug])
+      unless group
         site = _cama_get_field_site
         values[:parent_id] = site.id if site.present?
         group = if is_a?(CamaleonCms::Post) # harcoded for post to support custom field groups
@@ -206,6 +194,7 @@ def add_custom_field_group(values, kind = 'Post')
                   get_field_groups(kind).create!(values)
                 end
       end
+
       group
     end
     alias add_field_group add_custom_field_group
@@ -215,8 +204,8 @@ def add_custom_field_group(values, kind = 'Post')
     # more details in add_manual_field(item, options) from custom field groups
     # kind: argument only for PostType model: (Post | Category | PostTag), default => Post
     def add_custom_field_to_default_group(item, options, kind = 'Post')
-      g = get_field_groups(kind).where(slug: '_default').first
-      g = add_custom_field_group({ name: 'Default Field Group', slug: '_default' }, kind) unless g.present?
+      g = get_field_groups(kind).find_by(slug: '_default')
+      g ||= add_custom_field_group({ name: 'Default Field Group', slug: '_default' }, kind)
       g.add_manual_field(item, options)
     end
     alias add_field add_custom_field_to_default_group
@@ -260,7 +249,7 @@ def set_field_values(datas = {})
     # update new value for field with slug _key
     # Sample: my_posy.update_field_value('sub_title', 'Test Sub Title')
     def update_field_value(_key, value = nil, group_number = 0)
-      custom_field_values.where(custom_field_slug: _key, group_number: group_number).first.update_column('value', value)
+      custom_field_values.find_by(custom_field_slug: _key, group_number: group_number)&.update_column('value', value)
     rescue StandardError
       nil
     end
@@ -287,7 +276,7 @@ def save_field_value(key, value, order = 0, clear = true)
     # sample: my_post.set_field_value('subtitle', 'Sub Title', {group_number: 1})
     # sample: my_post.set_field_value('subtitle', 'Sub Title', {group_number: 1, group_number: 1}) # add field values for fields in group 1
     def set_field_value(key, value, args = {})
-      args = { order: 0, group_number: 0, field_id: nil, clear: true }.merge(args)
+      args = { order: 0, group_number: 0, field_id: nil, clear: true }.merge!(args)
       unless args[:field_id].present?
         args[:field_id] = begin
           get_field_object(key).id