diff --git a/.changesets/sanitize-activerecord::recordnotunique-error-messages.md b/.changesets/sanitize-activerecord::recordnotunique-error-messages.md
new file mode 100644
index 000000000..449819b67
--- /dev/null
+++ b/.changesets/sanitize-activerecord::recordnotunique-error-messages.md
@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "add"
+---
+
+Sanitize `ActiveRecord::RecordNotUnique` error messages to not include any database values that is not unique in the database. This ensures no personal information is sent to AppSignal through error messages from this error.
diff --git a/lib/appsignal/transaction.rb b/lib/appsignal/transaction.rb
index df662fe08..809664e0b 100644
--- a/lib/appsignal/transaction.rb
+++ b/lib/appsignal/transaction.rb
@@ -537,7 +537,7 @@ def cleaned_backtrace(backtrace)
     # Returns an unchanged message otherwise.
     def cleaned_error_message(error)
       case error.class.to_s
-      when "PG::UniqueViolation"
+      when "PG::UniqueViolation", "ActiveRecord::RecordNotUnique"
         error.message.to_s.gsub(/\)=\(.*\)/, ")=(?)")
       else
         error.message.to_s
diff --git a/spec/lib/appsignal/transaction_spec.rb b/spec/lib/appsignal/transaction_spec.rb
index 02f9e24ea..43dec9ed1 100644
--- a/spec/lib/appsignal/transaction_spec.rb
+++ b/spec/lib/appsignal/transaction_spec.rb
@@ -1364,6 +1364,25 @@ def session_exists?(_env)
         expect(subject).to eq "ERROR: duplicate key value violates unique constraint \"index_users_on_email\" DETAIL: Key (email)=(?) already exists."
       end
     end
+
+    context "with a ActiveRecord::RecordNotUnique" do
+      before do
+        stub_const("ActiveRecord::RecordNotUnique", Class.new(StandardError))
+      end
+
+      let(:error) do
+        ActiveRecord::RecordNotUnique.new(
+          "PG::UniqueViolation: ERROR: duplicate key value violates unique constraint \"example_constraint\"\n" \
+          "DETAIL: Key (email)=(foo@example.com) already exists."
+        )
+      end
+
+      it "returns a sanizited error message" do
+        expect(subject).to eq \
+          "PG::UniqueViolation: ERROR: duplicate key value violates unique constraint \"example_constraint\"\n" \
+          "DETAIL: Key (email)=(?) already exists."
+      end
+    end
   end
 
   describe ".to_hash / .to_h" do