diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 325b400e..f741c256 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,35 +9,43 @@ jobs:
         include:
           - ruby: 2.5
             gemfile: "gemfiles/Gemfile.rails-6.1-sprockets-3"
+            bundler: "2.3.0"
           - ruby: 2.5
             gemfile: "gemfiles/Gemfile.rails-6.1-sprockets-4"
-
+            bundler: "2.3.0"
           - ruby: 2.7
             gemfile: "gemfiles/Gemfile.rails-7.0-sprockets-3"
+            bundler: "2.4.8"
           - ruby: 2.7
             gemfile: "gemfiles/Gemfile.rails-7.0-sprockets-4"
-
+            bundler: "2.4.8"
           - ruby: 2.7
             gemfile: "gemfiles/Gemfile.rails-7.1-sprockets-3"
+            bundler: "2.4.8"
           - ruby: 2.7
             gemfile: "gemfiles/Gemfile.rails-7.1-sprockets-4"
-
+            bundler: "2.4.8"
           - ruby: 3.1
             gemfile: "gemfiles/Gemfile.rails-7.2-sprockets-3"
+            bundler: default
           - ruby: 3.1
             gemfile: "gemfiles/Gemfile.rails-7.2-sprockets-4"
-
+            bundler: default
           - ruby: 3.2
             gemfile: "gemfiles/Gemfile.rails-8.0-sprockets-3"
+            bundler: default
           - ruby: 3.2
             gemfile: "gemfiles/Gemfile.rails-8.0-sprockets-4"
-
+            bundler: default
           - ruby: 3.2
             gemfile: Gemfile
+            bundler: default
           - ruby: 3.3
             gemfile: Gemfile
+            bundler: default
           - ruby: head
             gemfile: Gemfile
+            bundler: default
 
     env:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
@@ -49,6 +57,8 @@ jobs:
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler-cache: true
+          cache-version: ${{ matrix.ruby }}-${{ matrix.ruby }}-${{ matrix.gemfile }}
+          bundler: ${{ matrix.bundler }}
       - name: Run tests
         run: bundle exec rake
         continue-on-error: ${{ matrix.gemfile == 'Gemfile' }}
diff --git a/gemfiles/Gemfile.rails-6.1-sprockets-3 b/gemfiles/Gemfile.rails-6.1-sprockets-3
index 3e31a785..0626d619 100644
--- a/gemfiles/Gemfile.rails-6.1-sprockets-3
+++ b/gemfiles/Gemfile.rails-6.1-sprockets-3
@@ -4,3 +4,5 @@ gemspec path: '..'
 gem 'actionpack', '~> 6.1.0'
 gem 'railties', '~> 6.1.0'
 gem 'sprockets', '~> 3.0'
+
+gem 'concurrent-ruby', '< 1.3.5'
diff --git a/gemfiles/Gemfile.rails-6.1-sprockets-4 b/gemfiles/Gemfile.rails-6.1-sprockets-4
index af14533e..41a6c57a 100644
--- a/gemfiles/Gemfile.rails-6.1-sprockets-4
+++ b/gemfiles/Gemfile.rails-6.1-sprockets-4
@@ -4,3 +4,5 @@ gemspec path: '..'
 gem 'actionpack', '~> 6.1.0'
 gem 'railties', '~> 6.1.0'
 gem 'sprockets', '~> 4.0'
+
+gem 'concurrent-ruby', '< 1.3.5'
diff --git a/gemfiles/Gemfile.rails-7.0-sprockets-3 b/gemfiles/Gemfile.rails-7.0-sprockets-3
index dd25e0ec..c5787efb 100644
--- a/gemfiles/Gemfile.rails-7.0-sprockets-3
+++ b/gemfiles/Gemfile.rails-7.0-sprockets-3
@@ -4,3 +4,5 @@ gemspec path: '..'
 gem 'actionpack', '~> 7.0.0'
 gem 'railties', '~> 7.0.0'
 gem 'sprockets', '~> 3.0'
+
+gem 'concurrent-ruby', '< 1.3.5'
diff --git a/gemfiles/Gemfile.rails-7.0-sprockets-4 b/gemfiles/Gemfile.rails-7.0-sprockets-4
index 27b9dd95..0c73b078 100644
--- a/gemfiles/Gemfile.rails-7.0-sprockets-4
+++ b/gemfiles/Gemfile.rails-7.0-sprockets-4
@@ -4,3 +4,5 @@ gemspec path: '..'
 gem 'actionpack', '~> 7.0.0'
 gem 'railties', '~> 7.0.0'
 gem 'sprockets', '~> 4.0'
+
+gem 'concurrent-ruby', '< 1.3.5'
diff --git a/lib/sprockets/railtie.rb b/lib/sprockets/railtie.rb
index 5f579e9c..1a774269 100644
--- a/lib/sprockets/railtie.rb
+++ b/lib/sprockets/railtie.rb
@@ -60,21 +60,6 @@ module Sprockets
   class Railtie < ::Rails::Railtie
     include Sprockets::Rails::Utils
 
-    class ManifestNeededError < StandardError
-      def initialize
-        msg = "Expected to find a manifest file in `app/assets/config/manifest.js`\n" +
-        "But did not, please create this file and use it to link any assets that need\n" +
-        "to be rendered by your app:\n\n" +
-        "Example:\n" +
-        "  //= link_tree ../images\n"  +
-        "  //= link_directory ../javascripts .js\n" +
-        "  //= link_directory ../stylesheets .css\n"  +
-        "and restart your server\n\n" +
-        "For more information see: https://github.com/rails/sprockets/blob/070fc01947c111d35bb4c836e9bb71962a8e0595/UPGRADING.md#manifestjs"
-        super msg
-      end
-    end
-
     LOOSE_APP_ASSETS = lambda do |logical_path, filename|
       filename.start_with?(::Rails.root.join("app/assets").to_s) &&
       !['.js', '.css', ''].include?(File.extname(logical_path))
@@ -103,8 +88,20 @@ def configure(&block)
 
     initializer :set_default_precompile do |app|
       if using_sprockets4?
-        raise ManifestNeededError unless ::Rails.root.join("app/assets/config/manifest.js").exist?
-        app.config.assets.precompile += %w( manifest.js )
+        if ::Rails.root.join("app/assets/config/manifest.js").exist?
+          app.config.assets.precompile += %w( manifest.js )
+        else
+          msg = "Expected to find a manifest file in `app/assets/config/manifest.js`\n" +
+          "But did not, please create this file and use it to link any assets that need\n" +
+          "to be rendered by your app:\n\n" +
+          "Example:\n" +
+          "  //= link_tree ../images\n"  +
+          "  //= link_directory ../javascripts .js\n" +
+          "  //= link_directory ../stylesheets .css\n"  +
+          "and restart your server\n\n" +
+          "For more information see: https://github.com/rails/sprockets/blob/070fc01947c111d35bb4c836e9bb71962a8e0595/UPGRADING.md#manifestjs"
+          Sprockets::Rails.deprecator.warn msg
+        end
       else
         app.config.assets.precompile += [LOOSE_APP_ASSETS, /(?:\/|\\|\A)application\.(css|js)$/]
       end