diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4f6e8a798..b0b0d6776 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## Unreleased (6.0.0)
+
+### Breaking Changes
+
+- Remove `config.async` ([#1894](https://github.com/getsentry/sentry-ruby/pull/1894))
+- Remove `config.capture_exception_frame_locals` ([#2306](https://github.com/getsentry/sentry-ruby/pull/2306))
+
 ## Unreleased
 
 ### Features
diff --git a/sentry-rails/examples/rails-6.0/config/initializers/sentry.rb b/sentry-rails/examples/rails-6.0/config/initializers/sentry.rb
index c0b0d08fb..70cb1aa18 100644
--- a/sentry-rails/examples/rails-6.0/config/initializers/sentry.rb
+++ b/sentry-rails/examples/rails-6.0/config/initializers/sentry.rb
@@ -5,7 +5,7 @@
   config.traces_sample_rate = 1.0 # set a float between 0.0 and 1.0 to enable performance monitoring
   config.dsn = 'https://2fb45f003d054a7ea47feb45898f7649@o447951.ingest.sentry.io/5434472'
   config.release = `git branch --show-current`
-  config.capture_exception_frame_locals = true
+  config.include_local_variables = true
   # you can use the pre-defined job for the async callback
   #
   # config.async = lambda do |event, hint|
diff --git a/sentry-rails/examples/rails-7.0/config/initializers/sentry.rb b/sentry-rails/examples/rails-7.0/config/initializers/sentry.rb
index c0b0d08fb..70cb1aa18 100644
--- a/sentry-rails/examples/rails-7.0/config/initializers/sentry.rb
+++ b/sentry-rails/examples/rails-7.0/config/initializers/sentry.rb
@@ -5,7 +5,7 @@
   config.traces_sample_rate = 1.0 # set a float between 0.0 and 1.0 to enable performance monitoring
   config.dsn = 'https://2fb45f003d054a7ea47feb45898f7649@o447951.ingest.sentry.io/5434472'
   config.release = `git branch --show-current`
-  config.capture_exception_frame_locals = true
+  config.include_local_variables = true
   # you can use the pre-defined job for the async callback
   #
   # config.async = lambda do |event, hint|
diff --git a/sentry-rails/lib/sentry/rails/active_job.rb b/sentry-rails/lib/sentry/rails/active_job.rb
index cf0c7ca1a..f2e0fc8a0 100644
--- a/sentry-rails/lib/sentry/rails/active_job.rb
+++ b/sentry-rails/lib/sentry/rails/active_job.rb
@@ -23,12 +23,7 @@ def record(job, &block)
             Sentry.with_scope do |scope|
               begin
                 scope.set_transaction_name(job.class.name, source: :task)
-                transaction =
-                  if job.is_a?(::Sentry::SendEventJob)
-                    nil
-                  else
-                    Sentry.start_transaction(name: scope.transaction_name, source: scope.transaction_source, op: OP_NAME)
-                  end
+                transaction = Sentry.start_transaction(name: scope.transaction_name, source: scope.transaction_source, op: OP_NAME)
 
                 scope.set_span(transaction) if transaction
 
diff --git a/sentry-rails/spec/dummy/test_rails_app/app.rb b/sentry-rails/spec/dummy/test_rails_app/app.rb
index af5a54400..184e1d079 100644
--- a/sentry-rails/spec/dummy/test_rails_app/app.rb
+++ b/sentry-rails/spec/dummy/test_rails_app/app.rb
@@ -82,7 +82,7 @@ def self.name
       config.transport.transport_class = Sentry::DummyTransport
       # for sending events synchronously
       config.background_worker_threads = 0
-      config.capture_exception_frame_locals = true
+      config.include_local_variables = true
       yield(config, app) if block_given?
     end
   end
diff --git a/sentry-rails/spec/sentry/rails/activejob_spec.rb b/sentry-rails/spec/sentry/rails/activejob_spec.rb
index f4d1550be..8c8eb33c1 100644
--- a/sentry-rails/spec/sentry/rails/activejob_spec.rb
+++ b/sentry-rails/spec/sentry/rails/activejob_spec.rb
@@ -230,50 +230,6 @@ def perform
       event = transport.events.last.to_json_compatible
       expect(event.dig("exception", "values", 0, "type")).to eq("ZeroDivisionError")
     end
-
-    context "and in user-defined reporting job too" do
-      before do
-        Sentry.configuration.async = lambda do |event, hint|
-          UserDefinedReportingJob.perform_now(event, hint)
-        end
-      end
-
-      class UserDefinedReportingJob < ActiveJob::Base
-        def perform(event, hint)
-          Post.find(0)
-        rescue
-          raise ActiveJob::DeserializationError
-        end
-      end
-
-      it "doesn't cause infinite loop because of excluded exceptions" do
-        expect do
-          DeserializationErrorJob.perform_now
-        end.to raise_error(ActiveJob::DeserializationError, /divided by 0/)
-      end
-    end
-
-    context "and in customized SentryJob too" do
-      before do
-        class CustomSentryJob < ::Sentry::SendEventJob
-          def perform(event, hint)
-            raise "Not excluded exception"
-          rescue
-            raise ActiveJob::DeserializationError
-          end
-        end
-
-        Sentry.configuration.async = lambda do |event, hint|
-          CustomSentryJob.perform_now(event, hint)
-        end
-      end
-
-      it "doesn't cause infinite loop" do
-        expect do
-          DeserializationErrorJob.perform_now
-        end.to raise_error(ActiveJob::DeserializationError, /divided by 0/)
-      end
-    end
   end
 
   context 'using rescue_from' do
diff --git a/sentry-rails/spec/sentry/send_event_job_spec.rb b/sentry-rails/spec/sentry/send_event_job_spec.rb
deleted file mode 100644
index c50130f65..000000000
--- a/sentry-rails/spec/sentry/send_event_job_spec.rb
+++ /dev/null
@@ -1,103 +0,0 @@
-require "active_job"
-require "spec_helper"
-
-RSpec.describe "Sentry::SendEventJob" do
-  let(:event) do
-    Sentry.get_current_client.event_from_message("test message")
-  end
-  let(:transport) do
-    Sentry.get_current_client.transport
-  end
-
-  context "when ActiveJob is not loaded" do
-    before do
-      TempActiveJob = ActiveJob
-      Object.send(:remove_const, "ActiveJob")
-      reload_send_event_job
-    end
-
-    after do
-      ActiveJob = TempActiveJob
-      reload_send_event_job
-    end
-
-    it "gets defined as a blank class" do
-      expect(Sentry::SendEventJob.superclass).to eq(Object)
-    end
-  end
-
-  context "when ActiveJob is loaded" do
-    after do
-      reload_send_event_job
-    end
-
-    it "reports events to Sentry" do
-      make_basic_app
-
-      Sentry.configuration.before_send = lambda do |event, hint|
-        event.tags[:hint] = hint
-        event
-      end
-
-      Sentry::SendEventJob.perform_now(event, { foo: "bar" })
-
-      expect(transport.events.count).to eq(1)
-      event = transport.events.first
-      expect(event.message).to eq("test message")
-      expect(event.tags[:hint][:foo]).to eq("bar")
-    end
-
-    it "doesn't create a new transaction" do
-      make_basic_app do |config|
-        config.traces_sample_rate = 1.0
-      end
-
-      Sentry::SendEventJob.perform_now(event)
-
-      expect(transport.events.count).to eq(1)
-      event = transport.events.first
-      expect(event.type).to eq("event")
-    end
-
-    context "when ApplicationJob is not defined" do
-      before do
-        make_basic_app
-      end
-      it "uses ActiveJob::Base as the parent class" do
-        expect(Sentry::SendEventJob.superclass).to eq(ActiveJob::Base)
-      end
-    end
-
-    context "when ApplicationJob is defined" do
-      before do
-        class ApplicationJob < ActiveJob::Base; end
-        reload_send_event_job
-        make_basic_app
-      end
-
-      after do
-        Object.send(:remove_const, "ApplicationJob")
-      end
-
-      it "uses ApplicationJob as the parent class" do
-        expect(Sentry::SendEventJob.superclass).to eq(ApplicationJob)
-      end
-    end
-
-    context "when ApplicationJob is defined but it's something else" do
-      before do
-        class ApplicationJob; end
-        reload_send_event_job
-        make_basic_app
-      end
-
-      after do
-        Object.send(:remove_const, "ApplicationJob")
-      end
-
-      it "uses ActiveJob::Base as the parent class" do
-        expect(Sentry::SendEventJob.superclass).to eq(ActiveJob::Base)
-      end
-    end
-  end
-end
diff --git a/sentry-ruby/examples/crons/README.md b/sentry-ruby/examples/crons/README.md
index 7430bde64..ec2951b36 100644
--- a/sentry-ruby/examples/crons/README.md
+++ b/sentry-ruby/examples/crons/README.md
@@ -1,7 +1,7 @@
 # sentry-ruby Crons example
 
 Crons monitoring allows you to track that certain that should be performed
-on a certain schedule are indeed performed on time and without errors. See 
+on a certain schedule are indeed performed on time and without errors. See
 [documentation](https://docs.sentry.io/platforms/ruby/crons/) for more details.
 
 This example project has a few rake tasks that manually send monitor check-ins
diff --git a/sentry-ruby/lib/sentry/background_worker.rb b/sentry-ruby/lib/sentry/background_worker.rb
index ee5b94305..1ee429d76 100644
--- a/sentry-ruby/lib/sentry/background_worker.rb
+++ b/sentry-ruby/lib/sentry/background_worker.rb
@@ -24,10 +24,7 @@ def initialize(configuration)
       @shutdown_callback = nil
 
       @executor =
-        if configuration.async
-          log_debug("config.async is set, BackgroundWorker is disabled")
-          Concurrent::ImmediateExecutor.new
-        elsif @number_of_threads == 0
+        if @number_of_threads == 0
           log_debug("config.background_worker_threads is set to 0, all events will be sent synchronously")
           Concurrent::ImmediateExecutor.new
         else
diff --git a/sentry-ruby/lib/sentry/client.rb b/sentry-ruby/lib/sentry/client.rb
index 608c4e1d5..a04287919 100644
--- a/sentry-ruby/lib/sentry/client.rb
+++ b/sentry-ruby/lib/sentry/client.rb
@@ -53,8 +53,7 @@ def capture_event(event, scope, hint = {})
         return
       end
 
-      event_type = event.is_a?(Event) ? event.type : event["type"]
-      data_category = Envelope::Item.data_category(event_type)
+      data_category = Envelope::Item.data_category(event.type)
       event = scope.apply_to_event(event, hint)
 
       if event.nil?
@@ -63,9 +62,7 @@ def capture_event(event, scope, hint = {})
         return
       end
 
-      if async_block = configuration.async
-        dispatch_async_event(async_block, event, hint)
-      elsif configuration.background_worker_threads != 0 && hint.fetch(:background, true)
+      if configuration.background_worker_threads != 0 && hint.fetch(:background, true)
         queued = dispatch_background_event(event, hint)
         transport.record_lost_event(:queue_overflow, data_category) unless queued
       else
@@ -166,10 +163,9 @@ def event_from_transaction(transaction)
 
     # @!macro send_event
     def send_event(event, hint = nil)
-      event_type = event.is_a?(Event) ? event.type : event["type"]
-      data_category = Envelope::Item.data_category(event_type)
+      data_category = Envelope::Item.data_category(event.type)
 
-      if event_type != TransactionEvent::TYPE && configuration.before_send
+      if event.type != TransactionEvent::TYPE && configuration.before_send
         event = configuration.before_send.call(event, hint)
 
         if event.nil?
@@ -179,7 +175,7 @@ def send_event(event, hint = nil)
         end
       end
 
-      if event_type == TransactionEvent::TYPE && configuration.before_send_transaction
+      if event.type == TransactionEvent::TYPE && configuration.before_send_transaction
         event = configuration.before_send_transaction.call(event, hint)
 
         if event.nil?
@@ -254,28 +250,5 @@ def dispatch_background_event(event, hint)
         send_event(event, hint)
       end
     end
-
-    def dispatch_async_event(async_block, event, hint)
-      # We have to convert to a JSON-like hash, because background job
-      # processors (esp ActiveJob) may not like weird types in the event hash
-
-      event_hash =
-        begin
-          event.to_json_compatible
-        rescue => e
-          log_error("Converting #{event.type} (#{event.event_id}) to JSON compatible hash failed", e, debug: configuration.debug)
-          return
-        end
-
-      if async_block.arity == 2
-        hint = JSON.parse(JSON.generate(hint))
-        async_block.call(event_hash, hint)
-      else
-        async_block.call(event_hash)
-      end
-    rescue => e
-      log_error("Async #{event_hash["type"]} sending failed", e, debug: configuration.debug)
-      send_event(event, hint)
-    end
   end
 end
diff --git a/sentry-ruby/lib/sentry/configuration.rb b/sentry-ruby/lib/sentry/configuration.rb
index a44fa21a1..3b004b36f 100644
--- a/sentry-ruby/lib/sentry/configuration.rb
+++ b/sentry-ruby/lib/sentry/configuration.rb
@@ -25,13 +25,6 @@ class Configuration
     # @return [Regexp, nil]
     attr_accessor :app_dirs_pattern
 
-    # Provide an object that responds to `call` to send events asynchronously.
-    # E.g.: lambda { |event| Thread.new { Sentry.send_event(event) } }
-    #
-    # @deprecated It will be removed in the next major release. Please read https://github.com/getsentry/sentry-ruby/issues/1522 for more information
-    # @return [Proc, nil]
-    attr_reader :async
-
     # to send events in a non-blocking way, sentry-ruby has its own background worker
     # by default, the worker holds a thread pool that has [the number of processors] threads
     # but you can configure it with this configuration option
@@ -73,7 +66,6 @@ class Configuration
     # @example
     #   config.before_send = lambda do |event, hint|
     #     # skip ZeroDivisionError exceptions
-    #     # note: hint[:exception] would be a String if you use async callback
     #     if hint[:exception].is_a?(ZeroDivisionError)
     #       nil
     #     else
@@ -159,18 +151,6 @@ class Configuration
     # @return [Boolean, String]
     attr_accessor :spotlight
 
-    # @deprecated Use {#include_local_variables} instead.
-    alias_method :capture_exception_frame_locals, :include_local_variables
-
-    # @deprecated Use {#include_local_variables=} instead.
-    def capture_exception_frame_locals=(value)
-      log_warn <<~MSG
-        `capture_exception_frame_locals` is now deprecated in favor of `include_local_variables`.
-      MSG
-
-      self.include_local_variables = value
-    end
-
     # You may provide your own LineCache for matching paths with source files.
     # This may be useful if you need to get source code from places other than the disk.
     # @see LineCache
@@ -409,22 +389,6 @@ def release=(value)
       @release = value
     end
 
-    def async=(value)
-      check_callable!("async", value)
-
-      log_warn <<~MSG
-
-        sentry-ruby now sends events asynchronously by default with its background worker (supported since 4.1.0).
-        The `config.async` callback has become redundant while continuing to cause issues.
-        (The problems of `async` are detailed in https://github.com/getsentry/sentry-ruby/issues/1522)
-
-        Therefore, we encourage you to remove it and let the background worker take care of async job sending.
-      It's deprecation is planned in the next major release (6.0), which is scheduled around the 3rd quarter of 2022.
-      MSG
-
-      @async = value
-    end
-
     def breadcrumbs_logger=(logger)
       loggers =
         if logger.is_a?(Array)
diff --git a/sentry-ruby/lib/sentry/transport.rb b/sentry-ruby/lib/sentry/transport.rb
index 326dcbf35..6efb32533 100644
--- a/sentry-ruby/lib/sentry/transport.rb
+++ b/sentry-ruby/lib/sentry/transport.rb
@@ -127,10 +127,7 @@ def envelope_from_event(event)
         sent_at: Sentry.utc_now.iso8601
       }
 
-      if event.is_a?(Event) && event.dynamic_sampling_context
-        envelope_headers[:trace] = event.dynamic_sampling_context
-      end
-
+      envelope_headers[:trace] = event.dynamic_sampling_context if event.dynamic_sampling_context
       envelope = Envelope.new(envelope_headers)
 
       envelope.add_item(
diff --git a/sentry-ruby/spec/sentry/background_worker_spec.rb b/sentry-ruby/spec/sentry/background_worker_spec.rb
index cefbc398b..885ff5df2 100644
--- a/sentry-ruby/spec/sentry/background_worker_spec.rb
+++ b/sentry-ruby/spec/sentry/background_worker_spec.rb
@@ -10,22 +10,6 @@
   end
 
   describe "#initialize" do
-    context "when config.async is set" do
-      before do
-        configuration.async = proc { }
-      end
-
-      it "initializes a background_worker with ImmediateExecutor" do
-        worker = described_class.new(configuration)
-
-        expect(string_io.string).to match(
-          /config.async is set, BackgroundWorker is disabled/
-        )
-
-        expect(worker.instance_variable_get(:@executor)).to be_a(Concurrent::ImmediateExecutor)
-      end
-    end
-
     context "when config.background_worker_threads is set" do
       it "initializes a background worker with correct number of threads and queue size" do
         worker = described_class.new(configuration)
diff --git a/sentry-ruby/spec/sentry/client/event_sending_spec.rb b/sentry-ruby/spec/sentry/client/event_sending_spec.rb
index 86098a469..2723b1a31 100644
--- a/sentry-ruby/spec/sentry/client/event_sending_spec.rb
+++ b/sentry-ruby/spec/sentry/client/event_sending_spec.rb
@@ -52,84 +52,6 @@
       end
     end
 
-    context 'with config.async set' do
-      let(:async_block) do
-        lambda do |event|
-          subject.send_event(event)
-        end
-      end
-
-      around do |example|
-        prior_async = configuration.async
-        configuration.async = async_block
-        example.run
-        configuration.async = prior_async
-      end
-
-      it "executes the given block" do
-        expect(async_block).to receive(:call).and_call_original
-
-        returned = subject.capture_event(event, scope)
-
-        expect(returned).to be_a(Sentry::ErrorEvent)
-        expect(subject.transport.events.first).to eq(event.to_json_compatible)
-      end
-
-      it "doesn't call the async block if not allow sending events" do
-        allow(configuration).to receive(:sending_allowed?).and_return(false)
-
-        expect(async_block).not_to receive(:call)
-
-        returned = subject.capture_event(event, scope)
-
-        expect(returned).to eq(nil)
-      end
-
-      context "with to json conversion failed" do
-        let(:logger) { ::Logger.new(string_io) }
-        let(:string_io) { StringIO.new }
-        let(:event) { subject.event_from_message("Bad data '\x80\xF8'") }
-
-        it "does not mask the exception" do
-          configuration.logger = logger
-
-          subject.capture_event(event, scope)
-
-          expect(string_io.string).to include("Converting event (#{event.event_id}) to JSON compatible hash failed: source sequence is illegal/malformed utf-8")
-        end
-      end
-
-      context "with nil as value (the legacy way to disable it)" do
-        let(:async_block) { nil }
-
-        it "doesn't cause any issue" do
-          returned = subject.capture_event(event, scope, { background: false })
-
-          expect(returned).to be_a(Sentry::ErrorEvent)
-          expect(subject.transport.events.first).to eq(event)
-        end
-      end
-
-      context "with 2 arity block" do
-        let(:async_block) do
-          lambda do |event, hint|
-            event["tags"]["hint"] = hint
-            subject.send_event(event)
-          end
-        end
-
-        it "serializes hint and supplies it as the second argument" do
-          expect(configuration.async).to receive(:call).and_call_original
-
-          returned = subject.capture_event(event, scope, { foo: "bar" })
-
-          expect(returned).to be_a(Sentry::ErrorEvent)
-          event = subject.transport.events.first
-          expect(event.dig("tags", "hint")).to eq({ "foo" => "bar" })
-        end
-      end
-    end
-
     context "with background_worker enabled (default)" do
       before do
         Sentry.background_worker = Sentry::BackgroundWorker.new(configuration)
@@ -207,22 +129,12 @@
 
       it "applies before_send callback before sending the event" do
         configuration.before_send = lambda do |event, _hint|
-          if event.is_a?(Sentry::Event)
-            event.tags[:called] = true
-          else
-            event["tags"]["called"] = true
-          end
-
+          event.tags[:called] = true
           event
         end
 
         subject.send_event(event)
-
-        if event.is_a?(Sentry::Event)
-          expect(event.tags[:called]).to eq(true)
-        else
-          expect(event["tags"]["called"]).to eq(true)
-        end
+        expect(event.tags[:called]).to eq(true)
       end
 
       it "doesn't apply before_send_transaction to Event" do
@@ -239,10 +151,6 @@
       let(:event) { event_object }
     end
 
-    it_behaves_like "Event in send_event" do
-      let(:event) { event_object.to_json_compatible }
-    end
-
     shared_examples "TransactionEvent in send_event" do
       it "sends data through the transport" do
         subject.send_event(event)
@@ -258,32 +166,18 @@
 
       it "applies before_send_transaction callback before sending the event" do
         configuration.before_send_transaction = lambda do |event, _hint|
-          if event.is_a?(Sentry::TransactionEvent)
-            event.tags[:called] = true
-          else
-            event["tags"]["called"] = true
-          end
-
+          event.tags[:called] = true
           event
         end
 
         subject.send_event(event)
-
-        if event.is_a?(Sentry::Event)
-          expect(event.tags[:called]).to eq(true)
-        else
-          expect(event["tags"]["called"]).to eq(true)
-        end
+        expect(event.tags[:called]).to eq(true)
       end
     end
 
     it_behaves_like "TransactionEvent in send_event" do
       let(:event) { transaction_event_object }
     end
-
-    it_behaves_like "TransactionEvent in send_event" do
-      let(:event) { transaction_event_object.to_json_compatible }
-    end
   end
 
   describe "integrated error handling testing with HTTPTransport" do
@@ -303,12 +197,6 @@
     let(:event) { subject.event_from_message(message) }
 
     describe "#capture_event" do
-      around do |example|
-        prior_async = configuration.async
-        example.run
-        configuration.async = prior_async
-      end
-
       context "when scope.apply_to_event returns nil" do
         before do
           scope.add_event_processor do |event, hint|
@@ -396,28 +284,6 @@
           expect(string_io.string).to match(/Event sending failed: TypeError/)
         end
       end
-
-      context "when config.async causes error" do
-        before do
-          expect(subject).to receive(:send_event)
-        end
-
-        it "swallows Redis related error and send the event synchronizely" do
-          configuration.async = ->(_, _) { raise Redis::ConnectionError }
-
-          subject.capture_event(event, scope)
-
-          expect(string_io.string).to match(/Async event sending failed: Redis::ConnectionError/)
-        end
-
-        it "swallows and logs the exception" do
-          configuration.async = ->(_, _) { raise TypeError }
-
-          subject.capture_event(event, scope)
-
-          expect(string_io.string).to match(/Async event sending failed: TypeError/)
-        end
-      end
     end
 
     describe "#send_event" do
diff --git a/sentry-ruby/spec/sentry/configuration_spec.rb b/sentry-ruby/spec/sentry/configuration_spec.rb
index 4ab21a101..a8ece9c63 100644
--- a/sentry-ruby/spec/sentry/configuration_spec.rb
+++ b/sentry-ruby/spec/sentry/configuration_spec.rb
@@ -1,29 +1,6 @@
 require 'spec_helper'
 
 RSpec.describe Sentry::Configuration do
-  describe "#capture_exception_frame_locals" do
-    it "passes/received the value to #include_local_variables" do
-      subject.capture_exception_frame_locals = true
-      expect(subject.include_local_variables).to eq(true)
-      expect(subject.capture_exception_frame_locals).to eq(true)
-
-      subject.capture_exception_frame_locals = false
-      expect(subject.include_local_variables).to eq(false)
-      expect(subject.capture_exception_frame_locals).to eq(false)
-    end
-
-    it "prints deprecation message when being assigned" do
-      string_io = StringIO.new
-      subject.logger = Logger.new(string_io)
-
-      subject.capture_exception_frame_locals = true
-
-      expect(string_io.string).to include(
-        "WARN -- sentry: `capture_exception_frame_locals` is now deprecated in favor of `include_local_variables`."
-      )
-    end
-  end
-
   describe "#csp_report_uri" do
     it "returns nil if the dsn is not present" do
       expect(subject.csp_report_uri).to eq(nil)
@@ -289,24 +266,11 @@
     end
   end
 
-  context 'configuring for async' do
-    it 'should be configurable to send events async' do
-      subject.async = ->(_e) { :ok }
-      expect(subject.async.call('event')).to eq(:ok)
-    end
-  end
-
   it 'raises error when setting release to anything other than String' do
     subject.release = "foo"
     expect { subject.release = 42 }.to raise_error(ArgumentError, "expect the argument to be a String or NilClass, got Integer (42)")
   end
 
-  it 'raises error when setting async to anything other than callable or nil' do
-    subject.async = -> { }
-    subject.async = nil
-    expect { subject.async = true }.to raise_error(ArgumentError, "async must be callable (or nil to disable)")
-  end
-
   it 'raises error when setting before_send to anything other than callable or nil' do
     subject.before_send = -> { }
     subject.before_send = nil
diff --git a/sentry-ruby/spec/sentry/transport/http_transport_rate_limiting_spec.rb b/sentry-ruby/spec/sentry/transport/http_transport_rate_limiting_spec.rb
index ac83e3b16..9698e6829 100644
--- a/sentry-ruby/spec/sentry/transport/http_transport_rate_limiting_spec.rb
+++ b/sentry-ruby/spec/sentry/transport/http_transport_rate_limiting_spec.rb
@@ -14,7 +14,7 @@
   let(:configuration) { Sentry.configuration }
   let(:client) { Sentry.get_current_client }
   let(:data) do
-    subject.envelope_from_event(client.event_from_message("foobarbaz").to_hash).to_s
+    subject.envelope_from_event(client.event_from_message("foobarbaz")).to_s
   end
 
   subject { Sentry::HTTPTransport.new(configuration) }
diff --git a/sentry-ruby/spec/sentry/transport/http_transport_spec.rb b/sentry-ruby/spec/sentry/transport/http_transport_spec.rb
index 3c7b1b051..1a70073ba 100644
--- a/sentry-ruby/spec/sentry/transport/http_transport_spec.rb
+++ b/sentry-ruby/spec/sentry/transport/http_transport_spec.rb
@@ -14,7 +14,7 @@
   let(:event) { client.event_from_message("foobarbaz") }
   let(:fake_time) { Time.now }
   let(:data) do
-    subject.serialize_envelope(subject.envelope_from_event(event.to_hash)).first
+    subject.serialize_envelope(subject.envelope_from_event(event)).first
   end
 
   subject { client.transport }
diff --git a/sentry-ruby/spec/sentry/transport/spotlight_transport_spec.rb b/sentry-ruby/spec/sentry/transport/spotlight_transport_spec.rb
index 04de57af6..ba6b23b25 100644
--- a/sentry-ruby/spec/sentry/transport/spotlight_transport_spec.rb
+++ b/sentry-ruby/spec/sentry/transport/spotlight_transport_spec.rb
@@ -18,7 +18,7 @@
   let(:client) { Sentry::Client.new(configuration) }
   let(:event) { client.event_from_message("foobarbaz") }
   let(:data) do
-    subject.serialize_envelope(subject.envelope_from_event(event.to_hash)).first
+    subject.serialize_envelope(subject.envelope_from_event(event)).first
   end
 
   subject { described_class.new(configuration) }
diff --git a/sentry-ruby/spec/sentry/transport_spec.rb b/sentry-ruby/spec/sentry/transport_spec.rb
index 7c90f4be7..2cf2dc9e1 100644
--- a/sentry-ruby/spec/sentry/transport_spec.rb
+++ b/sentry-ruby/spec/sentry/transport_spec.rb
@@ -387,18 +387,6 @@
         expect(io.string).to match(/Sending envelope with items \[event\]/)
       end
 
-      context "when the event hash has string keys" do
-        let(:envelope) { subject.envelope_from_event(event.to_json_compatible) }
-
-        it "deletes the event's breadcrumbs and sends it" do
-          expect(subject).to receive(:send_data)
-
-          subject.send_envelope(envelope)
-
-          expect(io.string).to match(/Sending envelope with items \[event\]/)
-        end
-      end
-
       context "if it's still oversized" do
         before do
           1000.times do |i|
@@ -450,12 +438,6 @@
         expect(subject.send_event(event)).to eq(event)
       end
 
-      it "sends Event hash" do
-        expect(subject).not_to receive(:failed_send)
-
-        expect(subject.send_event(event.to_json_compatible)).to eq(event.to_json_compatible)
-      end
-
       it "logs correct message" do
         expect(subject.send_event(event)).to eq(event)