diff --git a/app/controllers/concerns/authentication_stages.rb b/app/controllers/concerns/authentication_stages.rb
index 0322b6685b..947c7505e9 100644
--- a/app/controllers/concerns/authentication_stages.rb
+++ b/app/controllers/concerns/authentication_stages.rb
@@ -1,9 +1,9 @@
 module Concerns
   module AuthenticationStages
     def stage_success
-      stage = session[:authentication_stages].first
+      stage = session[:authentication_stages]&.first
 
-      if stage.to_s == params[:stage]
+      if stage && stage.to_s == params[:stage]
         if params[:secret] == stage_secrets[stage]
           session[:authentication_stages] = session[:authentication_stages].drop(1)
 
@@ -16,7 +16,7 @@ module Concerns
       else
         flash[:error] = I18n.t(
           :notice_auth_stage_wrong_stage,
-          expected: stage,
+          expected: stage || '(none)',
           actual: params[:stage]
         )
 
diff --git a/app/controllers/work_packages/moves_controller.rb b/app/controllers/work_packages/moves_controller.rb
index 4514d54be5..de22ce1668 100644
--- a/app/controllers/work_packages/moves_controller.rb
+++ b/app/controllers/work_packages/moves_controller.rb
@@ -121,7 +121,7 @@ class WorkPackages::MovesController < ApplicationController
   def check_project_uniqueness
     unless @project
       # TODO: let users bulk move/copy work packages from different projects
-      render_error I18n.t('work_packages.move.unsupported_for_multiple_projects')
+      render_error message: :'work_packages.move.unsupported_for_multiple_projects', status: 400
       return false
     end
   end
diff --git a/app/controllers/work_packages_controller.rb b/app/controllers/work_packages_controller.rb
index df9fd2a994..a139d0c078 100644
--- a/app/controllers/work_packages_controller.rb
+++ b/app/controllers/work_packages_controller.rb
@@ -58,6 +58,10 @@ class WorkPackagesController < ApplicationController
       format.atom do
         atom_journals
       end
+
+      format.all do
+        head :not_acceptable
+      end
     end
   end
 
diff --git a/app/models/enumeration.rb b/app/models/enumeration.rb
index 703839343e..a0aa1b194c 100644
--- a/app/models/enumeration.rb
+++ b/app/models/enumeration.rb
@@ -141,7 +141,9 @@ class Enumeration < ActiveRecord::Base
   # Does the +new+ Hash have the same custom values as the previous Enumeration?
   def self.same_custom_values?(new, previous)
     previous.custom_field_values.each do |custom_value|
-      if new && custom_value.value != new['custom_field_values'][custom_value.custom_field_id.to_s]
+      if new &&
+        new['custom_field_values'] &&
+        custom_value.value != new['custom_field_values'][custom_value.custom_field_id.to_s]
         return false
       end
     end
diff --git a/app/uploaders/file_uploader.rb b/app/uploaders/file_uploader.rb
index 92702644a3..77fc3b40b5 100644
--- a/app/uploaders/file_uploader.rb
+++ b/app/uploaders/file_uploader.rb
@@ -79,6 +79,8 @@ module FileUploader
   def cache!(new_file = sanitized_file)
     super
     @old_tmp_file = new_file
+  rescue => e
+    Rails.logger.error "Failed cache! of temporary upload file: #{e}"
   end
 
   def delete_old_tmp_file(_dummy)
diff --git a/modules/backlogs/lib/open_project/backlogs/burndown/series_raw_data.rb b/modules/backlogs/lib/open_project/backlogs/burndown/series_raw_data.rb
index ff6db136f0..669e2b358a 100644
--- a/modules/backlogs/lib/open_project/backlogs/burndown/series_raw_data.rb
+++ b/modules/backlogs/lib/open_project/backlogs/burndown/series_raw_data.rb
@@ -103,7 +103,7 @@ module OpenProject::Backlogs::Burndown
         AND #{fixed_version_query}
         AND #{project_id_query}
         AND #{type_id_query}
-        AND #{status_query}
+        #{and_status_query}
       JOIN
         (
           #{authoritative_journal_for_date(dates)}
@@ -149,7 +149,7 @@ module OpenProject::Backlogs::Burndown
                 AND #{fixed_version_query}
                 AND #{project_id_query}
                 AND #{type_id_query}
-                AND #{status_query})
+                #{and_status_query})
           GROUP BY
             CAST(j.created_at AS DATE),
             j.journable_type,
@@ -173,7 +173,7 @@ module OpenProject::Backlogs::Burndown
       }.join(' UNION ')
     end
 
-    def status_query
+    def and_status_query
       @status_query ||= begin
         non_closed_statuses = Status.where(is_closed: false).select(:id).map(&:id)
 
@@ -181,7 +181,11 @@ module OpenProject::Backlogs::Burndown
 
         open_status_ids = non_closed_statuses - done_statuses_for_project
 
-        "(#{Journal::WorkPackageJournal.table_name}.status_id IN (#{open_status_ids.join(',')}))"
+        if open_status_ids.empty?
+          ''
+        else
+          "AND (#{Journal::WorkPackageJournal.table_name}.status_id IN (#{open_status_ids.join(',')}))"
+        end
       end
     end
 
diff --git a/modules/webhooks/app/workers/work_package_webhook_job.rb b/modules/webhooks/app/workers/work_package_webhook_job.rb
index 3a1b9a8fe5..0ec3817b3c 100644
--- a/modules/webhooks/app/workers/work_package_webhook_job.rb
+++ b/modules/webhooks/app/workers/work_package_webhook_job.rb
@@ -30,6 +30,8 @@ require 'rest-client'
 #++
 
 class WorkPackageWebhookJob < WebhookJob
+  include ::OpenProjectErrorHelper
+
   attr_reader :webhook_id
   attr_reader :journal_id
   attr_reader :event_name
@@ -46,21 +48,22 @@ class WorkPackageWebhookJob < WebhookJob
     body = request_body
     headers = request_headers
     exception = nil
+    response = nil
 
     if signature = request_signature(body)
       headers['X-OP-Signature'] = signature
     end
 
-    response = RestClient.post webhook.url, request_body, headers
-  rescue RestClient::Exception => e
-    response = e.response
-
-    raise e
-  rescue => e
-    exception = e
+    begin
+      response = RestClient.post webhook.url, request_body, headers
+    rescue RestClient::Exception => e
+      response = e.response
+      exception = e
+    rescue StandardError => e
+      op_handle_error(e.message, reference: :webhook_job)
+      exception = e
+    end
 
-    raise e
-  ensure
     ::Webhooks::Log.create(
       webhook: webhook,
       event_name: event_name,