diff --git a/.rubocop.yml b/.rubocop.yml
index 9ff7d5e2f..55801c592 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,202 +1,2 @@
-inherit_from: .rubocop_todo.yml
-
 AllCops:
-  TargetRubyVersion: 2.5
-  TargetRailsVersion: 6.1
-
-  NewCops: enable
-
-  Exclude:
-    - '**/vendor/**/*'
-    - '**/tmp/**/*'
-    - '**/bin/**/*'
-    - '**/plugins/**/*'
-    - '**/extra/**/*'
-    - '**/lib/generators/**/templates/*'
-    - '**/lib/tasks/**/*'
-    - '**/files/**/*'
-    - 'db/schema.rb'
-
-# Enable extensions
-
-require:
-  - rubocop-performance
-  - rubocop-rails
-
-# Rules for Redmine
-
-Bundler/OrderedGems:
-  Enabled: false
-
-Layout/CaseIndentation:
-  Exclude:
-    - 'config/initializers/10-patches.rb'
-
-Layout/ClosingParenthesisIndentation:
-  Enabled: true
-  Exclude:
-    - 'lib/redmine/wiki_formatting/textile/redcloth3.rb'
-
-Layout/EmptyLinesAroundAccessModifier:
-  Enabled: true
-  Exclude:
-    - 'config/initializers/10-patches.rb'
-
-Layout/EmptyLineBetweenDefs:
-  AllowAdjacentOneLineDefs: true
-
-Layout/FirstHashElementIndentation:
-  Enabled: true
-  Exclude:
-    - 'lib/redmine/wiki_formatting/textile/redcloth3.rb'
-
-Layout/LineLength:
-  Enabled: true
-  IgnoredPatterns: ['\A\s+test \".+\" do\z', '\A\s*\#']
-  Exclude:
-    - 'db/migrate/0*.rb'
-    - 'db/migrate/1*.rb'
-    - 'db/migrate/201*.rb'
-    - 'db/migrate/20200*.rb'
-    - 'lib/redmine/wiki_formatting/textile/redcloth3.rb'
-
-Layout/RescueEnsureAlignment:
-  Enabled: true
-  Exclude:
-    - 'db/migrate/085_add_role_tracker_old_status_index_to_workflows.rb'
-
-Layout/SpaceAroundEqualsInParameterDefault:
-  Enabled: false
-
-Layout/SpaceBeforeSemicolon:
-  Enabled: true
-  Exclude:
-    - 'config/initializers/10-patches.rb'
-
-Layout/SpaceBeforeBlockBraces:
-  # "space" is used more than "no_space".
-  # But "no_space" is more natural in one liner.
-  #   str = path.to_s.split(%r{[/\\]}).select{|p| !p.blank?}.join("/")
-  Enabled: false
-
-Layout/SpaceInsideBlockBraces:
-  Enabled: false
-
-Layout/SpaceInsideHashLiteralBraces:
-  Enabled: false
-
-Lint/RaiseException:
-  Enabled: true
-
-Lint/StructNewOverride:
-  Enabled: true
-
-Lint/SuppressedException:
-  AllowComments: true
-
-Layout/TrailingWhitespace:
-  AllowInHeredoc: true
-
-Metrics:
-  Enabled: false
-
-Naming/AccessorMethodName:
-  Enabled: false
-
-Naming/VariableNumber:
-  CheckMethodNames: false
-  CheckSymbols: false
-
-Naming/BinaryOperatorParameterName:
-  Enabled: false
-
-Naming/PredicateName:
-  Enabled: false
-
-Rails/BulkChangeTable:
-  Exclude:
-    - 'db/migrate/20120714122200_add_workflows_rule_fields.rb'
-    - 'db/migrate/20131214094309_remove_custom_fields_min_max_length_default_values.rb'
-
-Rails/CompactBlank:
-  Enabled: false
-
-Rails/EnvironmentVariableAccess:
-  Enabled: false
-
-Rails/FilePath:
-  Enabled: false
-
-Rails/HelperInstanceVariable:
-  Enabled: false
-
-Style/AsciiComments:
-  Exclude:
-    # Copyright credit has non ascii character.
-    # We can not change nor remove it.
-    - 'app/models/repository/git.rb'
-
-Style/BlockComments:
-  Enabled: true
-  Exclude:
-    - 'lib/redmine/string_array_diff/diff.rb'
-    - 'lib/redmine/string_array_diff/diffable.rb'
-
-Style/BlockDelimiters:
-  Enabled: true
-  Exclude:
-    - 'db/migrate/007_create_journals.rb'
-    - 'lib/redmine/string_array_diff/diff.rb'
-    - 'lib/redmine/string_array_diff/diffable.rb'
-
-Style/EmptyElse:
-  EnforcedStyle: empty
-
-Style/FormatString:
-  EnforcedStyle: sprintf
-
-Style/FormatStringToken:
-  Enabled: false
-
-Style/FrozenStringLiteralComment:
-  Enabled: true
-  EnforcedStyle: always
-  Exclude:
-    - 'db/**/*.rb'
-    - 'Gemfile'
-    - 'Rakefile'
-    - 'config.ru'
-    - 'config/additional_environment.rb'
-
-Style/GlobalStdStream:
-  Enabled: false
-
-Style/HashEachMethods:
-  Enabled: true
-
-Style/HashSyntax:
-  Enabled: true
-  EnforcedStyle: no_mixed_keys
-
-Style/HashTransformKeys:
-  Enabled: true
-
-Style/HashTransformValues:
-  Enabled: true
-
-Style/IdenticalConditionalBranches:
-  Exclude:
-    - 'config/initializers/10-patches.rb'
-    - 'lib/redmine/wiki_formatting/textile/redcloth3.rb'
-
-Style/NegatedIfElseCondition:
-  Enabled: false
-
-Style/RaiseArgs:
-  Enabled: false
-
-Style/TrailingCommaInArrayLiteral:
-  Enabled: false
-
-Style/TrailingCommaInHashLiteral:
-  Enabled: false
+  DisabledByDefault: true
diff --git a/Gemfile b/Gemfile
index 29d639b9a..c2167512f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -99,10 +99,6 @@ group :test do
   gem 'capybara', (Gem.ruby_version < Gem::Version.new('2.6.0') ? '~> 3.35.3' : '~> 3.36.0')
   gem "selenium-webdriver", "~> 3.142.7"
   gem 'webdrivers', '4.6.1', require: false
-  # RuboCop
-  gem 'rubocop', '~> 1.26.0'
-  gem 'rubocop-performance', '~> 1.13.0'
-  gem 'rubocop-rails', '~> 2.14.0'
 end
 
 local_gemfile = File.join(File.dirname(__FILE__), "Gemfile.local")
diff --git a/app/models/query.rb b/app/models/query.rb
index 7695bc165..4d4fdafdf 100644
--- a/app/models/query.rb
+++ b/app/models/query.rb
@@ -1160,9 +1160,10 @@ class Query < ActiveRecord::Base
       where = "(#{where}) AND #{db_table}.#{db_field} <> ''"
     end
     "#{queried_table_name}.#{customized_key} #{not_in} IN (" \
-      "SELECT #{customized_class.table_name}.id FROM #{customized_class.table_name}" \
+      "SELECT #{customized_class.table_name}.id FROM #{customized_class.table_name} AS cf_issue" \
       " LEFT OUTER JOIN #{db_table} ON #{db_table}.customized_type='#{customized_class}'" \
-      " AND #{db_table}.customized_id=#{customized_class.table_name}.id" \
+      " AND #{db_table}.customized_id=cf_issue.id" \
+      " AND #{customized_class.table_name}.id=cf_issue.id " \
       " AND #{db_table}.custom_field_id=#{custom_field_id}" \
       " WHERE (#{where}) AND (#{filter[:field].visibility_by_project_condition}))"
   end