diff --git a/.ruby-version b/.ruby-version
index bea438e9..9c25013d 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.1
+3.3.6
diff --git a/Gemfile.lock b/Gemfile.lock
index 2a1e5c3d..0e5b26f3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -99,7 +99,7 @@ GEM
       msgpack (~> 1.2)
     brakeman (6.2.2)
       racc
-    bson (5.0.1)
+    bson (5.0.2)
     builder (3.3.0)
     byebug (11.1.3)
     carrierwave (2.2.6)
@@ -126,7 +126,7 @@ GEM
     database_cleaner-mongoid (2.0.1)
       database_cleaner-core (~> 2.0.0)
       mongoid
-    date (3.3.4)
+    date (3.4.0)
     diff-lcs (1.5.1)
     dig_rb (1.0.1)
     docile (1.4.1)
@@ -140,18 +140,18 @@ GEM
     factory_bot_rails (6.4.4)
       factory_bot (~> 6.5)
       railties (>= 5.0.0)
-    faraday (2.12.0)
-      faraday-net_http (>= 2.0, < 3.4)
+    faraday (2.12.1)
+      faraday-net_http (>= 2.0, < 3.5)
       json
       logger
-    faraday-net_http (3.3.0)
-      net-http
+    faraday-net_http (3.4.0)
+      net-http (>= 0.5.0)
     ffi (1.17.0)
     ffi (1.17.0-aarch64-linux-gnu)
     ffi (1.17.0-arm64-darwin)
     ffi (1.17.0-x86_64-linux-gnu)
     find_a_port (1.0.1)
-    gds-api-adapters (96.0.3)
+    gds-api-adapters (97.3.0)
       addressable
       link_header
       null_logger
@@ -199,7 +199,7 @@ GEM
       govuk_app_config (>= 1.1)
       redis-client (>= 0.22.2)
       sidekiq (~> 7.0, < 8)
-    hashdiff (1.1.1)
+    hashdiff (1.1.2)
     hashie (5.0.0)
     http-accept (1.7.0)
     http-cookie (1.0.7)
@@ -242,11 +242,11 @@ GEM
     mime-types (3.6.0)
       logger
       mime-types-data (~> 3.2015)
-    mime-types-data (3.2024.1001)
+    mime-types-data (3.2024.1105)
     mini_magick (4.13.2)
     mini_mime (1.1.5)
-    mini_portile2 (2.8.7)
-    minitest (5.25.1)
+    mini_portile2 (2.8.8)
+    minitest (5.25.2)
     mongo (2.21.0)
       bson (>= 4.14.1, < 6.0.0)
     mongoid (8.1.7)
@@ -254,15 +254,15 @@ GEM
       concurrent-ruby (>= 1.0.5, < 2.0)
       mongo (>= 2.18.0, < 3.0.0)
       ruby2_keywords (~> 0.0.5)
-    mongoid-grid_fs (2.5.0)
+    mongoid-grid_fs (2.6.0)
       mime-types (>= 1.0, < 4.0)
-      mongoid (>= 3.0, < 9.0)
-    msgpack (1.7.2)
+      mongoid (>= 3.0, < 10.0)
+    msgpack (1.7.5)
     multi_xml (0.7.1)
       bigdecimal (~> 3.1)
-    net-http (0.4.1)
+    net-http (0.5.0)
       uri
-    net-imap (0.5.0)
+    net-imap (0.5.1)
       date
       net-protocol
     net-pop (0.1.2)
@@ -331,7 +331,7 @@ GEM
     opentelemetry-instrumentation-active_model_serializers (0.20.2)
       opentelemetry-api (~> 1.0)
       opentelemetry-instrumentation-base (~> 0.22.1)
-    opentelemetry-instrumentation-active_record (0.8.0)
+    opentelemetry-instrumentation-active_record (0.8.1)
       opentelemetry-api (~> 1.0)
       opentelemetry-instrumentation-base (~> 0.22.1)
     opentelemetry-instrumentation-active_support (0.6.0)
@@ -498,7 +498,7 @@ GEM
       opentelemetry-semantic_conventions
     opentelemetry-semantic_conventions (1.10.1)
       opentelemetry-api (~> 1.0)
-    ostruct (0.6.0)
+    ostruct (0.6.1)
     pact (1.65.3)
       pact-mock_service (~> 3.0, >= 3.3.1)
       pact-support (~> 1.16, >= 1.16.9)
@@ -506,11 +506,12 @@ GEM
       rainbow (~> 3.1)
       rspec (~> 3.0)
       thor (>= 0.20, < 2.0)
-    pact-mock_service (3.11.2)
+    pact-mock_service (3.12.3)
       find_a_port (~> 1.0.1)
       json
       pact-support (~> 1.16, >= 1.16.4)
-      rack (~> 2.0)
+      rack (>= 3.0, < 4.0)
+      rackup (~> 2.0)
       rspec (>= 2.14)
       thor (>= 0.19, < 2.0)
       webrick (~> 1.8)
@@ -542,20 +543,20 @@ GEM
     puma (6.4.3)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (2.2.10)
-    rack-protection (3.2.0)
+    rack (3.1.8)
+    rack-protection (4.1.1)
       base64 (>= 0.1.0)
-      rack (~> 2.2, >= 2.2.4)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
     rack-proxy (0.7.7)
       rack
-    rack-session (1.0.2)
-      rack (< 3)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
     rack-test (2.1.0)
       rack (>= 1.3)
     rack_strip_client_ip (0.0.2)
-    rackup (1.0.1)
-      rack (< 3)
-      webrick
+    rackup (2.2.1)
+      rack (>= 3)
     rails (7.2.2)
       actioncable (= 7.2.2)
       actionmailbox (= 7.2.2)
@@ -594,7 +595,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rdoc (6.7.0)
+    rdoc (6.8.1)
       psych (>= 4.0.0)
     redis-client (0.22.2)
       connection_pool
@@ -680,8 +681,7 @@ GEM
     sentry-sidekiq (5.21.0)
       sentry-ruby (~> 5.21.0)
       sidekiq (>= 3.0)
-    sidekiq (7.3.2)
-      concurrent-ruby (< 2)
+    sidekiq (7.3.6)
       connection_pool (>= 2.3.0)
       logger
       rack (>= 2.2.4)
@@ -706,7 +706,7 @@ GEM
       actionpack (>= 6.1)
       activesupport (>= 6.1)
       sprockets (>= 3.0.0)
-    ssrf_filter (1.1.2)
+    ssrf_filter (1.2.0)
     state_machines (0.6.0)
     state_machines-activemodel (0.9.0)
       activemodel (>= 6.0)
@@ -721,14 +721,14 @@ GEM
     term-ansicolor (1.11.2)
       tins (~> 1.0)
     thor (1.3.2)
-    timeout (0.4.1)
+    timeout (0.4.2)
     tins (1.37.0)
       bigdecimal
       sync
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
     unicode-display_width (2.6.0)
-    uri (0.13.1)
+    uri (1.0.2)
     useragent (0.16.10)
     version_gem (1.1.4)
     warden (1.2.9)
diff --git a/README.md b/README.md
index ef61885a..4ed89135 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ You can use the [GOV.UK Docker environment](https://github.com/alphagov/govuk-do
 
 All assets are uploaded to the S3 bucket via a separate `govuk_sidekiq` job triggered if virus scanning succeeds. Assets are currently still also saved to the NFS mount as per the original behaviour.
 
-In non-production environments if the `AWS_S3_BUCKET_NAME` environment variable is not set, then a fake version of S3 (`S3Storage::Fake`) is used and the other `AWS_*` environment variables do not need to be set. In this case, files are saved to the local filesystem instead of S3 and are served via an instance of `Rack::File` mounted on the appropriate route path prefix.
+In non-production environments if the `AWS_S3_BUCKET_NAME` environment variable is not set, then a fake version of S3 (`S3Storage::Fake`) is used and the other `AWS_*` environment variables do not need to be set. In this case, files are saved to the local filesystem instead of S3 and are served via an instance of `Rack::Files` mounted on the appropriate route path prefix.
 
 ### Manuals and decisions
 
diff --git a/config/routes.rb b/config/routes.rb
index 32d9b4e1..5438d31f 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -18,7 +18,7 @@
   get "/government/uploads/*path" => "whitehall_media#download"
 
   if AssetManager.s3.fake?
-    mount Rack::File.new(AssetManager.fake_s3.root), at: AssetManager.fake_s3.path_prefix, as: "fake_s3"
+    mount Rack::Files.new(AssetManager.fake_s3.root), at: AssetManager.fake_s3.path_prefix, as: "fake_s3"
   end
 
   require "sidekiq_unique_jobs/web"