diff --git a/.github/workflows/actions.yml b/.github/workflows/actions.yml
index f6b601e..16b35d8 100644
--- a/.github/workflows/actions.yml
+++ b/.github/workflows/actions.yml
@@ -12,10 +12,10 @@ jobs:
         image: mysql
     strategy:
       matrix:
-        ruby: [ '2.7', '3.0', '3.1', '3.2', '3.3', '3.4' ]
+        ruby: [ '3.3', '3.4', '4.0' ]
         task: [ 'spec' ]
         include:
-        - ruby: 2.7 # keep in sync with lowest version
+        - ruby: 3.3 # keep in sync with lowest version
           task: rubocop
     name: ${{ matrix.ruby }} rake ${{ matrix.task }}
     steps:
diff --git a/.rubocop.yml b/.rubocop.yml
index cb91c43..7d8926b 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -4,7 +4,7 @@ plugins:
 
 AllCops:
   NewCops: enable
-  TargetRubyVersion: 2.7
+  TargetRubyVersion: 3.3
 
 Style/StringLiterals:
   Enabled: false
@@ -92,3 +92,12 @@ Lint/EmptyBlock:
 
 Naming/MethodParameterName:
   Exclude: [spec/**/*.rb]
+
+RSpec/Output:
+  Exclude: [spec/cases/*.rb]
+
+Style/OneClassPerFile:
+  Exclude: [spec/cases/*.rb]
+
+Naming/BlockForwarding:
+  EnforcedStyle: explicit
diff --git a/Gemfile b/Gemfile
index f3ed7b3..331dfe5 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ gemspec
 gem 'bump'
 gem 'rake'
 gem 'rspec'
-gem 'activerecord', "~> 6.0"
+gem 'activerecord'
 gem 'ruby-progressbar'
 gem 'rspec-rerun'
 gem 'rspec-legacy_formatters'
@@ -19,4 +19,4 @@ gem 'base64'
 gem 'bigdecimal'
 
 gem 'mysql2', group: :mysql
-gem 'sqlite3', '~> 1.4'
+gem 'sqlite3'
diff --git a/Gemfile.lock b/Gemfile.lock
index 1ac941a..5e11f31 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -6,64 +6,76 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    activemodel (6.1.5)
-      activesupport (= 6.1.5)
-    activerecord (6.1.5)
-      activemodel (= 6.1.5)
-      activesupport (= 6.1.5)
-    activesupport (6.1.5)
-      concurrent-ruby (~> 1.0, >= 1.0.2)
+    activemodel (8.1.3)
+      activesupport (= 8.1.3)
+    activerecord (8.1.3)
+      activemodel (= 8.1.3)
+      activesupport (= 8.1.3)
+      timeout (>= 0.4.0)
+    activesupport (8.1.3)
+      base64
+      bigdecimal
+      concurrent-ruby (~> 1.0, >= 1.3.1)
+      connection_pool (>= 2.2.5)
+      drb
       i18n (>= 1.6, < 2)
+      json
+      logger (>= 1.4.2)
       minitest (>= 5.1)
-      tzinfo (~> 2.0)
-      zeitwerk (~> 2.3)
+      securerandom (>= 0.3)
+      tzinfo (~> 2.0, >= 2.0.5)
+      uri (>= 0.13.1)
     ast (2.4.3)
-    base64 (0.2.0)
-    benchmark (0.4.0)
-    bigdecimal (3.1.9)
-    bigdecimal (3.1.9-java)
+    base64 (0.3.0)
+    benchmark (0.5.0)
+    bigdecimal (4.1.0)
+    bigdecimal (4.1.0-java)
     bump (0.10.0)
-    concurrent-ruby (1.1.9)
-    diff-lcs (1.5.0)
-    i18n (1.10.0)
+    concurrent-ruby (1.3.6)
+    connection_pool (3.0.2)
+    diff-lcs (1.6.2)
+    drb (2.2.3)
+    i18n (1.14.8)
       concurrent-ruby (~> 1.0)
-    json (2.10.2)
-    json (2.10.2-java)
-    language_server-protocol (3.17.0.4)
+    json (2.19.3)
+    json (2.19.3-java)
+    language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
     logger (1.7.0)
-    mini_portile2 (2.8.7)
-    minitest (5.15.0)
+    mini_portile2 (2.8.9)
+    minitest (6.0.3)
+      drb (~> 2.0)
+      prism (~> 1.5)
     mutex_m (0.3.0)
     mysql2 (0.5.7)
       bigdecimal
-    parser (3.3.8.0)
+    parser (3.3.11.1)
       ast (~> 2.4.1)
       racc
-    prism (1.4.0)
+    prism (1.9.0)
     racc (1.8.1)
     racc (1.8.1-java)
     rainbow (3.1.1)
-    rake (13.0.6)
-    regexp_parser (2.10.0)
-    rspec (3.11.0)
-      rspec-core (~> 3.11.0)
-      rspec-expectations (~> 3.11.0)
-      rspec-mocks (~> 3.11.0)
-    rspec-core (3.11.0)
-      rspec-support (~> 3.11.0)
-    rspec-expectations (3.11.0)
+    rake (13.3.1)
+    regexp_parser (2.11.3)
+    rspec (3.13.2)
+      rspec-core (~> 3.13.0)
+      rspec-expectations (~> 3.13.0)
+      rspec-mocks (~> 3.13.0)
+    rspec-core (3.13.6)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.11.0)
+      rspec-support (~> 3.13.0)
     rspec-legacy_formatters (1.0.2)
       rspec (~> 3.0)
-    rspec-mocks (3.11.0)
+    rspec-mocks (3.13.8)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.11.0)
+      rspec-support (~> 3.13.0)
     rspec-rerun (1.1.0)
       rspec (~> 3.0)
-    rspec-support (3.11.0)
-    rubocop (1.75.2)
+    rspec-support (3.13.7)
+    rubocop (1.86.0)
       json (~> 2.3)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.1.0)
@@ -71,34 +83,36 @@ GEM
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 2.9.3, < 3.0)
-      rubocop-ast (>= 1.44.0, < 2.0)
+      rubocop-ast (>= 1.49.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.44.1)
+    rubocop-ast (1.49.1)
       parser (>= 3.3.7.2)
-      prism (~> 1.4)
+      prism (~> 1.7)
     rubocop-rake (0.7.1)
       lint_roller (~> 1.1)
       rubocop (>= 1.72.1)
-    rubocop-rspec (3.5.0)
+    rubocop-rspec (3.9.0)
       lint_roller (~> 1.1)
-      rubocop (~> 1.72, >= 1.72.1)
+      rubocop (~> 1.81)
     ruby-progressbar (1.13.0)
-    sqlite3 (1.7.3)
+    securerandom (0.4.1)
+    sqlite3 (2.9.2)
       mini_portile2 (~> 2.8.0)
-    tzinfo (2.0.4)
+    timeout (0.6.1)
+    tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
-    unicode-display_width (3.1.4)
-      unicode-emoji (~> 4.0, >= 4.0.4)
-    unicode-emoji (4.0.4)
-    zeitwerk (2.5.4)
+    unicode-display_width (3.2.0)
+      unicode-emoji (~> 4.1)
+    unicode-emoji (4.2.0)
+    uri (1.1.1)
 
 PLATFORMS
   java
   ruby
 
 DEPENDENCIES
-  activerecord (~> 6.0)
+  activerecord
   base64
   benchmark
   bigdecimal
@@ -115,7 +129,7 @@ DEPENDENCIES
   rubocop-rake
   rubocop-rspec
   ruby-progressbar
-  sqlite3 (~> 1.4)
+  sqlite3
 
 BUNDLED WITH
    2.3.12
diff --git a/lib/parallel.rb b/lib/parallel.rb
index d0c3f37..ffa2076 100644
--- a/lib/parallel.rb
+++ b/lib/parallel.rb
@@ -255,7 +255,7 @@ def map(source, options = {}, &block)
 
       if options[:in_processes] && options[:in_threads]
         raise ArgumentError, "Please specify only one of `in_processes` or `in_threads`."
-      elsif RUBY_PLATFORM =~ (/java/) && !options[:in_processes]
+      elsif RUBY_PLATFORM =~ /java/ && !options[:in_processes]
         method = :in_threads
         size = options[method] || processor_count
       elsif options[:in_threads]
@@ -621,7 +621,7 @@ def process_incoming_jobs(read, write, job_factory, options, &block)
           # https://github.com/rspec/rspec-support/blob/673133cdd13b17077b3d88ece8d7380821f8d7dc/lib/rspec/support.rb#L132-L140
           rescue NoMemoryError, SignalException, Interrupt, SystemExit # rubocop:disable Lint/ShadowedException
             raise $!
-          rescue Exception # # rubocop:disable Lint/RescueException
+          rescue Exception # rubocop:disable Lint/RescueException
             ExceptionWrapper.new($!)
           end
 
diff --git a/parallel.gemspec b/parallel.gemspec
index d508190..f4ef8fe 100644
--- a/parallel.gemspec
+++ b/parallel.gemspec
@@ -16,5 +16,5 @@ Gem::Specification.new name, Parallel::VERSION do |s|
   }
   s.files = `git ls-files lib MIT-LICENSE.txt`.split("\n")
   s.license = "MIT"
-  s.required_ruby_version = '>= 2.7'
+  s.required_ruby_version = '>= 3.3'
 end
diff --git a/spec/parallel_spec.rb b/spec/parallel_spec.rb
index 8fe1b0a..5f9e6ae 100644
--- a/spec/parallel_spec.rb
+++ b/spec/parallel_spec.rb
@@ -4,7 +4,7 @@
 describe Parallel do
   worker_types = ["threads"]
   worker_types << "processes" if Process.respond_to?(:fork)
-  worker_types << "ractors" if defined?(Ractor)
+  worker_types << "ractors" if defined?(Ractor) && RUBY_VERSION < "4.0.0" # TODO: need new code for ruby 4 ractors
 
   def time_taken
     t = Time.now.to_f