diff --git a/app/controllers/api/v1/invoice_generator/invoice_generator_controller.rb b/app/controllers/api/v1/invoice_generator/invoice_generator_controller.rb
index ee5c88b..b7c1fd5 100644
--- a/app/controllers/api/v1/invoice_generator/invoice_generator_controller.rb
+++ b/app/controllers/api/v1/invoice_generator/invoice_generator_controller.rb
@@ -31,12 +31,27 @@ class InvoiceGeneratorController < ApplicationController
         param :invoice_number, String, required: true
 
         def create
-          InvoiceInstanceGenerator.create(params:)
+          Rails.logger.info(
+            "[BILLING-GENERATE] start invoice_number=#{params[:invoice_number].inspect} " \
+            "initiator=#{params[:custom_field2].inspect} amount=#{params[:transaction_amount].inspect} " \
+            "request_id=#{request.request_id}"
+          )
+
+          invoice = InvoiceInstanceGenerator.create(params:)
           link = EverypayLinkGenerator.create(params:)
 
+          Rails.logger.info(
+            "[BILLING-GENERATE] saved id=#{invoice&.id} invoice_number=#{invoice&.invoice_number} " \
+            "request_id=#{request.request_id}"
+          )
+
           render json: { 'message' => 'Link created', 'everypay_link' => link }, status: :created
         rescue StandardError => e
-          Rails.logger.info e
+          Rails.logger.error(
+            "[BILLING-GENERATE] FAILED invoice_number=#{params[:invoice_number].inspect} " \
+            "request_id=#{request.request_id} -> #{e.class}: #{e.message}"
+          )
+          Rails.logger.error(e.backtrace.join("\n")) if e.backtrace
         end
       end
     end
diff --git a/app/controllers/api/v1/invoice_generator/invoice_number_generator_controller.rb b/app/controllers/api/v1/invoice_generator/invoice_number_generator_controller.rb
index 4b0f4a9..fc373c3 100644
--- a/app/controllers/api/v1/invoice_generator/invoice_number_generator_controller.rb
+++ b/app/controllers/api/v1/invoice_generator/invoice_number_generator_controller.rb
@@ -4,6 +4,12 @@ class Api::V1::InvoiceGenerator::InvoiceNumberGeneratorController < Api::V1::Inv
   def create
     invoice_number = InvoiceNumberService.call
 
+    Rails.logger.info(
+      "[BILLING-NUMBER] generated=#{invoice_number.inspect} " \
+      "min=#{InvoiceNumberService::INVOICE_NUMBER_MIN} max=#{InvoiceNumberService::INVOICE_NUMBER_MAX} " \
+      "db_max=#{Invoice.maximum(:invoice_number).inspect} request_id=#{request.request_id}"
+    )
+
     if invoice_number == 'out of range'
       return render json: { 'message' => "Number create failed. #{invoice_number}",
                             'error' => invoice_number }, status: :not_implemented
diff --git a/app/controllers/api/v1/invoice_generator/oneoff_controller.rb b/app/controllers/api/v1/invoice_generator/oneoff_controller.rb
index abbca5e..95d6a83 100644
--- a/app/controllers/api/v1/invoice_generator/oneoff_controller.rb
+++ b/app/controllers/api/v1/invoice_generator/oneoff_controller.rb
@@ -11,14 +11,23 @@ class OneoffController < Api::V1::InvoiceGenerator::BaseController
         param :reference_number, String, required: false
 
         def create
+          Rails.logger.info(
+            "[BILLING-ONEOFF] start invoice_number=#{params[:invoice_number].inspect} " \
+            "customer_url=#{params[:customer_url].inspect} " \
+            "found_in_db=#{Invoice.exists?(invoice_number: params[:invoice_number])} " \
+            "request_id=#{request.request_id}"
+          )
+
           response = Oneoff.call(invoice_number: params[:invoice_number],
                                  customer_url: params[:customer_url],
                                  reference_number: params[:reference_number])
           if response.result?
+            Rails.logger.info("[BILLING-ONEOFF] ok invoice_number=#{params[:invoice_number].inspect} request_id=#{request.request_id}")
             render json: { 'message' => 'Link created',
                            'oneoff_redirect_link' => response.instance['payment_link'] },
                    status: :created
           else
+            Rails.logger.warn("[BILLING-ONEOFF] rejected invoice_number=#{params[:invoice_number].inspect} errors=#{response.errors.inspect} request_id=#{request.request_id}")
             render json: { error: response.errors }, status: :unprocessable_entity
           end
         end
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 612c927..91557c9 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -1,6 +1,16 @@
 class ApplicationController < ActionController::API
+  prepend_before_action :log_api_request
   before_action :authorized
 
+  def log_api_request
+    Rails.logger.info(
+      "[BILLING-API] #{request.request_method} #{request.original_fullpath} " \
+      "host=#{request.host} request_id=#{request.request_id} " \
+      "initiator=#{(decoded_token && decoded_token[0]['initiator']).inspect} " \
+      "params=#{request.filtered_parameters.except('controller', 'action', 'format').inspect}"
+    )
+  end
+
   def encode_token(payload)
     JWT.encode(payload, ENV['secret_word'])
   end
diff --git a/app/controllers/errors_controller.rb b/app/controllers/errors_controller.rb
index 32c3853..3f5e9e6 100644
--- a/app/controllers/errors_controller.rb
+++ b/app/controllers/errors_controller.rb
@@ -7,11 +7,39 @@ def show
                    ActionDispatch::ExceptionWrapper.new(
                      request.env, @exception
                    ).status_code
-    render view_for_code(@status_code), status: @status_code
+
+    log_exception
+
+    respond_to do |format|
+      format.html { render view_for_code(@status_code), status: @status_code }
+      format.json { render json: error_payload, status: @status_code }
+      format.any  { render json: error_payload, status: @status_code, content_type: 'application/json' }
+    end
   end
 
   private
 
+  def log_exception
+    return if @exception.nil?
+
+    wrapped = @exception.cause || @exception
+
+    Rails.logger.error(
+      "[ErrorsController] #{@status_code} on #{request.method} " \
+      "#{request.original_fullpath} (format=#{request.format.try(:ref).inspect}) " \
+      "request_id=#{request.request_id} -> " \
+      "#{wrapped.class}: #{wrapped.message}"
+    )
+    Rails.logger.error(wrapped.backtrace.join("\n")) if wrapped.backtrace
+  end
+
+  def error_payload
+    {
+      error: Rack::Utils::HTTP_STATUS_CODES.fetch(@status_code, 'Error'),
+      status: @status_code
+    }
+  end
+
   def view_for_code(code)
     supported_error_codes.fetch(code, '404')
   end
diff --git a/app/views/errors/401.html.erb b/app/views/errors/401.html.erb
new file mode 100644
index 0000000..c1c8286
--- /dev/null
+++ b/app/views/errors/401.html.erb
@@ -0,0 +1,3 @@
+<h1 class='text-2xl font-bold mb-8'>Unauthorized</h1>
+
+<%= link_to 'Back to home', root_path, class: 'text-indigo-500' %>
diff --git a/app/views/errors/404.html.erb b/app/views/errors/404.html.erb
new file mode 100644
index 0000000..5983d0c
--- /dev/null
+++ b/app/views/errors/404.html.erb
@@ -0,0 +1,3 @@
+<h1 class='text-2xl font-bold mb-8'>Not Found</h1>
+
+<%= link_to 'Back to home', root_path, class: 'text-indigo-500' %>
diff --git a/app/views/errors/500.html.erb b/app/views/errors/500.html.erb
new file mode 100644
index 0000000..6f7926a
--- /dev/null
+++ b/app/views/errors/500.html.erb
@@ -0,0 +1,3 @@
+<h1 class='text-2xl font-bold mb-8'>Internal Server Error</h1>
+
+<%= link_to 'Back to home', root_path, class: 'text-indigo-500' %>
diff --git a/config/application.yml.sample b/config/application.yml.sample
index 6a0919f..4ed80b6 100644
--- a/config/application.yml.sample
+++ b/config/application.yml.sample
@@ -76,7 +76,7 @@ development:
 tara_redirect_uri: 'https://eis_billing_system.test/auth/tara/callback'
 tara_identifier: ''
 tara_secret: ''
-tara_scope: 'openid'
+tara_scope: 'openid webauthn'
 tara_discovery: true
 
 
diff --git a/db/schema.rb b/db/schema.rb
index ff3262d..d4c543a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2023_11_30_114315) do
+ActiveRecord::Schema[7.2].define(version: 2023_11_30_114315) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"