diff --git a/.github/workflows/maze-runner.yml b/.github/workflows/maze-runner.yml
index e2e27582..0c31db33 100644
--- a/.github/workflows/maze-runner.yml
+++ b/.github/workflows/maze-runner.yml
@@ -127,7 +127,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby-version: ['2.7', '3.3']
+        ruby-version: ['2.7', '3.3.0'] # TODO: change back to '3.3' after https://github.com/ruby/ruby/pull/10619 is released
         rails-version: ['6', '7', '_integrations']
         include:
           - ruby-version: '2.5'
@@ -135,7 +135,7 @@ jobs:
         exclude:
           - ruby-version: '2.7'
             rails-version: '6'
-          - ruby-version: '3.3'
+          - ruby-version: '3.3.0' # TODO: change back to '3.3' after https://github.com/ruby/ruby/pull/10619 is released
             rails-version: '_integrations'
 
     uses: ./.github/workflows/run-maze-runner.yml
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 111dc799..f8b5bec1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,16 @@
 Changelog
 =========
 
+## v6.27.0 (23 May 2024)
+
+### Enhancements
+
+* Include the Warden scope in user metadata
+  | [#821](https://github.com/bugsnag/bugsnag-ruby/pull/821)
+  | [javierjulio](https://github.com/javierjulio)
+* Add a block variant of `add_on_error`
+  | [#824](https://github.com/bugsnag/bugsnag-ruby/pull/824)
+
 ## v6.26.4 (25 March 2024)
 
 ### Fixes
diff --git a/VERSION b/VERSION
index 30bfaeb1..9cd1a39f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.26.4
+6.27.0
diff --git a/lib/bugsnag.rb b/lib/bugsnag.rb
index 5d002a90..950f1726 100644
--- a/lib/bugsnag.rb
+++ b/lib/bugsnag.rb
@@ -309,6 +309,20 @@ def leave_breadcrumb(name, meta_data={}, type=Bugsnag::Breadcrumbs::MANUAL_BREAD
       configuration.breadcrumbs << breadcrumb unless breadcrumb.ignore?
     end
 
+    ##
+    # Add the given block to the list of on_error callbacks
+    #
+    # The on_error callbacks will be called when an error is captured or reported
+    # and are passed a {Bugsnag::Report} object
+    #
+    # Returning false from an on_error callback will cause the error to be ignored
+    # and will prevent any remaining callbacks from being called
+    #
+    # @return [void]
+    def on_error(&block)
+      configuration.on_error(&block)
+    end
+
     ##
     # Add the given callback to the list of on_error callbacks
     #
diff --git a/lib/bugsnag/configuration.rb b/lib/bugsnag/configuration.rb
index 36dda53d..bcf64c81 100644
--- a/lib/bugsnag/configuration.rb
+++ b/lib/bugsnag/configuration.rb
@@ -569,6 +569,20 @@ def disable_sessions
       @enable_sessions = false
     end
 
+    ##
+    # Add the given block to the list of on_error callbacks
+    #
+    # The on_error callbacks will be called when an error is captured or reported
+    # and are passed a {Bugsnag::Report} object
+    #
+    # Returning false from an on_error callback will cause the error to be ignored
+    # and will prevent any remaining callbacks from being called
+    #
+    # @return [void]
+    def on_error(&block)
+      middleware.use(block)
+    end
+
     ##
     # Add the given callback to the list of on_error callbacks
     #
diff --git a/lib/bugsnag/middleware/warden_user.rb b/lib/bugsnag/middleware/warden_user.rb
index 59c6af0d..bb9b8432 100644
--- a/lib/bugsnag/middleware/warden_user.rb
+++ b/lib/bugsnag/middleware/warden_user.rb
@@ -23,7 +23,10 @@ def call(report)
           # Extract useful user information
           user = {}
           user_object = env["warden"].user({:scope => best_scope, :run_callbacks => false}) rescue nil
+
           if user_object
+            user[:warden_scope] = best_scope
+
             # Build the user info for this scope
             COMMON_USER_FIELDS.each do |field|
               user[field] = user_object.send(field) if user_object.respond_to?(field)
diff --git a/spec/integrations/warden_user_spec.rb b/spec/integrations/warden_user_spec.rb
index 03b0b5fd..1a228d9a 100644
--- a/spec/integrations/warden_user_spec.rb
+++ b/spec/integrations/warden_user_spec.rb
@@ -6,33 +6,100 @@
 
     user = double
     allow(user).to receive_messages(
-      :email => "TEST_EMAIL",
-      :name => "TEST_NAME",
-      :created_at => "TEST_NOW"
+      email: "TEST_EMAIL",
+      name: "TEST_NAME",
+      created_at: "TEST_NOW",
     )
 
     warden = double
     allow(warden).to receive(:user).with({
-      :scope => "user",
-      :run_callbacks => false
+      scope: "user",
+      run_callbacks: false,
     }).and_return(user)
 
     report = double("Bugsnag::Report") 
+    expect(report).to receive(:request_data).exactly(3).times.and_return({
+      rack_env: {
+        "warden" => warden,
+        "rack.session" => {
+          "warden.user.user.key" => "TEST_USER",
+        }
+      }
+    })
+
+    expect(report).to receive(:user=).with({
+      email: "TEST_EMAIL",
+      name: "TEST_NAME",
+      created_at: "TEST_NOW",
+      warden_scope: "user",
+    })
+
+    expect(callback).to receive(:call).with(report)
+
+    middleware = Bugsnag::Middleware::WardenUser.new(callback)
+    middleware.call(report)
+  end
+
+  it "sets the scope to the 'best scope'" do
+    callback = double
+
+    user = double
+    allow(user).to receive_messages(
+      email: "TEST_EMAIL",
+      name: "TEST_NAME",
+      created_at: "TEST_NOW",
+    )
+
+    warden = double
+    allow(warden).to receive(:user).with({
+      scope: "admin",
+      run_callbacks: false,
+    }).and_return(user)
+
+    report = double("Bugsnag::Report")
     expect(report).to receive(:request_data).exactly(3).times.and_return({
       :rack_env => {
         "warden" => warden,
         "rack.session" => {
-          "warden.user.user.key" => "TEST_USER"
+          "warden.user.admin.key" => "TEST_USER"
         }
       }
     })
 
     expect(report).to receive(:user=).with({
-      :email => "TEST_EMAIL",
-      :name => "TEST_NAME",
-      :created_at => "TEST_NOW"
+      email: "TEST_EMAIL",
+      name: "TEST_NAME",
+      created_at: "TEST_NOW",
+      warden_scope: "admin",
+    })
+
+    expect(callback).to receive(:call).with(report)
+
+    middleware = Bugsnag::Middleware::WardenUser.new(callback)
+    middleware.call(report)
+  end
+
+  it "doesn't set the user if the user object is empty" do
+    callback = double
+
+    warden = double
+    allow(warden).to receive(:user).with({
+      scope: "user",
+      run_callbacks: false,
+    }).and_return(nil)
+
+    report = double("Bugsnag::Report")
+    expect(report).to receive(:request_data).exactly(3).times.and_return({
+      :rack_env => {
+        "warden" => warden,
+        "rack.session" => {
+          "warden.user.user.key" => "TEST_USER"
+        }
+      }
     })
 
+    expect(report).not_to receive(:user=)
+
     expect(callback).to receive(:call).with(report)
 
     middleware = Bugsnag::Middleware::WardenUser.new(callback)
diff --git a/spec/on_error_spec.rb b/spec/on_error_spec.rb
index 15bcdb5a..798befd1 100644
--- a/spec/on_error_spec.rb
+++ b/spec/on_error_spec.rb
@@ -18,6 +18,20 @@
     end)
   end
 
+  it "accepts a block" do
+    Bugsnag.on_error {|report| report.add_tab(:important, { hello: "world" }) }
+    Bugsnag.on_error {|report| report.add_tab(:significant, { hey: "earth" }) }
+
+    Bugsnag.notify(RuntimeError.new("Oh no!"))
+
+    expect(Bugsnag).to(have_sent_notification do |payload, _headers|
+      event = get_event_from_payload(payload)
+
+      expect(event["metaData"]["important"]).to eq({ "hello" => "world" })
+      expect(event["metaData"]["significant"]).to eq({ "hey" => "earth" })
+    end)
+  end
+
   it "can add callbacks in a configure block" do
     callback1 = proc {|report| report.add_tab(:important, { hello: "world" }) }
     callback2 = proc {|report| report.add_tab(:significant, { hey: "earth" }) }
@@ -25,6 +39,9 @@
     Bugsnag.configure do |config|
       config.add_on_error(callback1)
       config.add_on_error(callback2)
+      config.on_error do |report|
+        report.add_tab(:critical, { hi: "planet" })
+      end
     end
 
     Bugsnag.notify(RuntimeError.new("Oh no!"))
@@ -34,6 +51,7 @@
 
       expect(event["metaData"]["important"]).to eq({ "hello" => "world" })
       expect(event["metaData"]["significant"]).to eq({ "hey" => "earth" })
+      expect(event["metaData"]["critical"]).to eq({ "hi" => "planet" })
     end)
   end
 
@@ -56,6 +74,27 @@
     end)
   end
 
+  it "can remove an already registered block" do
+    callback1 = proc {|report| report.add_tab(:important, { hello: "world" }) }
+    callback2 = proc {|report| report.add_tab(:significant, { hey: "earth" }) }
+
+    Bugsnag.add_on_error(callback1)
+
+    # pass callback2 as a block so that it can be removed
+    Bugsnag.on_error(&callback2)
+
+    Bugsnag.remove_on_error(callback2)
+
+    Bugsnag.notify(RuntimeError.new("Oh no!"))
+
+    expect(Bugsnag).to(have_sent_notification do |payload, _headers|
+      event = get_event_from_payload(payload)
+
+      expect(event["metaData"]["important"]).to eq({ "hello" => "world" })
+      expect(event["metaData"]["significant"]).to be_nil
+    end)
+  end
+
   it "can remove all registered callbacks" do
     callback1 = proc {|report| report.add_tab(:important, { hello: "world" }) }
     callback2 = proc {|report| report.add_tab(:significant, { hey: "earth" }) }