diff --git a/.bundle/config b/.bundle/config
new file mode 100644
index 00000000..704b057f
--- /dev/null
+++ b/.bundle/config
@@ -0,0 +1,3 @@
+---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e0df1a1a..a4cbdac7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,18 +12,34 @@ on:
 
 jobs:
   ci:
+    name: ${{ matrix.task }} ${{ matrix.ruby-version }} / java@${{ matrix.java-version }} / jruby-rack@${{ matrix.jruby-rack-version }}
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
-        java-version: [8, 21, 25]
-        ruby-version: [jruby-9.4, jruby-10.0, jruby-10.1]
         task: ['', integration]
+        java-version: [8, 17, 21, 25]
+        ruby-version: [jruby-9.4, jruby-10.0, jruby-10.1]
+        jruby-rack-version: ['1.2', '1.3', '2.0']
         exclude:
           - ruby-version: jruby-10.0  # JRuby 10 requires Java 21 minimum
             java-version: 8
           - ruby-version: jruby-10.1  # JRuby 10 requires Java 21 minimum
             java-version: 8
+          - ruby-version: jruby-10.0  # JRuby 10 requires Java 21 minimum
+            java-version: 17
+          - ruby-version: jruby-10.1  # JRuby 10 requires Java 21 minimum
+            java-version: 17
+          - task: 'integration'       # War integration tests require Java 17
+            java-version: 8
+          - jruby-rack-version: '1.3' # No need to vary jruby-rack version for non-integration
+            task: ''
+          - jruby-rack-version: '2.0' # No need to vary jruby-rack version for non-integration
+            task: ''
+          - jruby-rack-version: '1.3' # JRuby-Rack 1.3+ requires JRuby 10
+            ruby-version: jruby-9.4
+          - jruby-rack-version: '2.0' # JRuby-Rack 1.3+ requires JRuby 10
+            ruby-version: jruby-9.4
 
       fail-fast: false
 
@@ -54,4 +70,4 @@ jobs:
         run: BUNDLE_JOBS=1 bundle install
 
       - name: Run tests
-        run: bundle exec rake ${{ matrix.task }}
+        run: bundle exec rake ${{ matrix.task }} "JRUBY_RACK_VERSION='[${{ matrix.jruby-rack-version }},${{ matrix.jruby-rack-version }}.99999)'"
diff --git a/.gitignore b/.gitignore
index 619554af..c28ec59d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 !spec/rails7_stub/Gemfile.lock
 *.sqlite3-*
+!.bundle/config
 .bundle
 .idea
 .polyglot.Mavenfile
diff --git a/Mavenfile b/Mavenfile
index 2cb2b530..2f3e1597 100644
--- a/Mavenfile
+++ b/Mavenfile
@@ -10,13 +10,12 @@ properties(
   'project.build.sourceEncoding' => 'UTF-8',
   'mavengem.wagon.version' => '2.0.3',
   'jruby.plugins.version' => '3.0.6',
-  'jetty.version' => '9.4.58.v20250814',
+  'jruby-rack.version' => '[1.2,1.2.99999)',
 )
 
 # dependencies needed for compilation
 scope :provided do
   jar 'org.jruby:jruby', '${jruby.version}'
-  jar 'org.eclipse.jetty:jetty-webapp', '${jetty.version}'
 end
 
 plugin :clean, '3.5.0'
@@ -27,18 +26,19 @@ plugin :jar, '3.5.0' do
 end
 plugin :install, '3.1.4'
 
-gem 'bundler', '${bundler.version}'
+gem 'bundler', Bundler::VERSION
 gem 'jruby-jars', '${jruby.version}'
+gem 'jruby-rack', '${jruby-rack.version}'
 
 plugin :invoker, '3.10.1' do
   execute_goals( :install, :run,
                  :id => 'integration-test',
                  :properties => {
+                   'jruby.plugins.version' => '${jruby.plugins.version}',
                    'warbler.version' => '${project.version}',
                    'jruby.version' => '${jruby.version}',
-                   'jetty.version' => '${jetty.version}',
-                   'bundler.version' => '${bundler.version}',
-                   'jruby.plugins.version' => '${jruby.plugins.version}',
+                   'jruby-rack.version' => '${jruby-rack.version}',
+                   'java.ee.version' => '${java.ee.version}',
                    'style.color' => 'always',
                  },
                  :goals => ['verify'],
diff --git a/README.rdoc b/README.rdoc
index d4f68ef6..dec58910 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -12,14 +12,11 @@ Ruby applications to assemble and Just Work.
 
     Warbler  Status        JRuby     Java  JRuby-Rack    Rails    Notes
     -------  ----------  ----------  ----  ----------  ---------  ----------------------------------------------
-    2.1      Maintained  9.4 → 10.1  8+    1.2 → 1.3   5.0 → 8.0  Rails 8.1 may be OK with pure Ruby webservers.
+    2.1      Maintained  9.4 → 10.1  8+    1.2 → 2.0   5.0 → 8.0  Rails 8.1 may be OK with pure Ruby webservers.
     2.0      EOL         9.2 → 9.3   6+    1.1 → 1.2       → 6.1
     1.4      EOL         1.1 → 1.7   5+        ?           ?
 
-For running wars with specific Java web servers, consult jruby-rack compatibility (
-{master}[https://github.com/jruby/jruby-rack/tree/master],
-{1.2-stable}[https://github.com/jruby/jruby-rack/tree/1.2-stable],
-{1.1-stable}[https://github.com/jruby/jruby-rack/tree/1.1-stable] ).
+For running wars with specific Java web servers, consult {jruby-rack compatibility}[https://github.com/jruby/jruby-rack#compatibility].
 
 == Getting Started
 
@@ -256,10 +253,33 @@ task to give you more insight into what's going on.
 If you think you found a bug, please file one at
 https://github.com/jruby/warbler/issues.
 
-=== Common issues with executable wars
+=== Common issues with wars
 
 If your app isn't working or starting up correctly:
 
+-  <b>Jruby-Rack version not compatible with JRuby version</b>
+    jruby-rack-2.0.0 requires Ruby version >= 3.4.0. The current ruby version is 3.1.7.
+    jruby-rack-1.3.0 requires Ruby version >= 3.4.0. The current ruby version is 3.1.7.
+   Warbler is compatible with multiple JRuby-Rack versions which have different JRuby requirements. You are trying to use
+   a jruby-rack version which does not support your JRuby version; without using bundler to resolve dependencies.
+   - Consult {jruby-rack compatibility}[https://github.com/jruby/jruby-rack#compatibility] for intended target jruby-rack version
+   - Use a bundler `:development` group to install warbler, and ensure bundler is running with your intended runtime
+     JRuby version so the jruby-rack dependency is resolved correctly.
+
+-  <b>Rack version compatibility</b>
+    An exception happened during JRuby-Rack startup
+    no such file to load -- rack/chunked
+   You are trying to use Rack 3.x with a jruby-rack version that does not yet support Rack 3. Try upgrading to a compatible
+   jruby-rack version, or lock rack at a compatibile version with <tt>gem 'rack', '~> 2.2.0'</tt>. Note that Rack `2.2` requires Rails < `8.1`.
+
+-  <b>Rack missing at runtime</b>
+    org.jruby.exceptions.LoadError: (LoadError) cannot load such file -- rack
+    JRuby-Rack no longer vendors Rack - make sure the rack gem is available to the application (e.g. add it to the Gemfile or install it into the gem path)
+   You are trying to use JRuby-Rack 1.3+, without a bundle or gem path that resolves an appropriate Rack version via the
+   `jruby-rack` gem's runtime dependency. Try one of (with appropriate rack version):
+   - Bundler: add <tt>gem 'rack', '~> 2.2.0'</tt> or similar as a default/runtime dependency to your `Gemfile`
+   - Rubygems: add <tt>config.gems['rack'] = '~> 2.2.0'</tt> to your `config/warble.rb`
+
 -  <b>CompatVersion errors:</b>
    If you are getting <tt>java.lang.NoClassDefFoundError: org/jruby/CompatVersion</tt> errors at start-up
    you are probably running Warbler with a jruby-rack version which does not yet support JRuby 10+ - it 
@@ -270,25 +290,11 @@ If your app isn't working or starting up correctly:
    that probably means bundler is trying to switch versions dynamically during start-up because your
    `Gemfile.lock` implies a different locked version of bundler to that packaged with JRuby by default.
 
-   JRuby/Bundler running embedded inside a jar like this does not support switching bundler versions dynamically.
+   JRuby/Bundler running embedded inside a jar like this does not support switching bundler versions dynamically
+   - Ensure you're on warbler `2.1.2+` and/or jruby-rack `1.2.8+` which attempts to workaround this issue
+   - If that doesn't help, ensure you are using `BUNDLE_VERSION=system` when bundling/warbling your application to ensure
+     the identical embedded JRuby bundler version is used during warbling and runtime.
 
-   This may happen due to
-   - system gems for jruby installation upgradingg bundler to a newer version than packaged by default
-   - running <tt>bundle update --bundler</tt>
-   - using `BUNDLE_VERSION` to override bundle version which generating/editing your `Gemfile.lock`
-
-   Options to address this
-   - use <tt>bundle config set version system</tt> / <tt>bundle config set disable_shared_gems</tt> to avoid bundler picking system versions
-   - ensure your `Gemfile.lock`'s <tt>BUNDLED WITH</tt> version matches the default bundler packaged with your `jruby-jars` version. 
-     You can check inside the relevant `jruby-stdlib` jar or inside a clean installation dir from your Ruby version manager of choice. 
-   - remove <tt>BUNDLED WITH</tt> entirely from `Gemfile.lock`. Sometimes bundler will add this back again; so not recommended in the longer term
-
--  <b>Rack version compatibility</b>
-    An exception happened during JRuby-Rack startup
-    no such file to load -- rack/chunked
-   You are trying to use Rack 3.x with a jruby-rack version that does not yet support Rack 3. Try upgrading to a compatible
-   jruby-rack version, or lock rack at a compatibile version with <tt>gem 'rack', '~> 2.2.0'</tt>. Note that Rack `2.2` requires Rails < `8.1`.
-   
 == Source
 
 You can get the Warbler source using Git, in any of the following ways:
diff --git a/Rakefile b/Rakefile
index 5633eea3..8564988b 100644
--- a/Rakefile
+++ b/Rakefile
@@ -21,11 +21,15 @@ task :spec => :jar
 
 task :default => :spec
 
+jruby_rack_version = ENV['JRUBY_RACK_VERSION']
+java_ee_version = jruby_rack_version&.include?('[2.') ? 'ee11' : 'ee8'
+
 # use Mavenfile to define :jar task
 require 'maven/ruby/maven'
 mvn = Maven::Ruby::Maven.new
 mvn << "-Djruby.version=#{JRUBY_VERSION}"
-mvn << "-Dbundler.version=#{Bundler::VERSION}"
+mvn << "-Djruby-rack.version=#{jruby_rack_version}" if jruby_rack_version
+mvn << "-Djava.ee.version=#{java_ee_version}"
 mvn << '--no-transfer-progress'
 mvn << '--color=always'
 
diff --git a/integration/pom.xml b/integration/pom.xml
index 7d494dc9..5982088d 100644
--- a/integration/pom.xml
+++ b/integration/pom.xml
@@ -16,8 +16,8 @@
     <!-- Default versions, overridden from parent when running tests acros env -->
     <warbler.version>2.1.3.pre</warbler.version>
     <jruby.version>9.4.15.0</jruby.version>
-    <bundler.version>2.6.3</bundler.version>
-    <jetty.version>9.4.58.v20250814</jetty.version>
+    <jruby-rack.version>[1.2,1.2.99999)</jruby-rack.version>
+    <java.ee.version>ee8</java.ee.version>
   </properties>
 
   <repositories>
@@ -28,12 +28,6 @@
   </repositories>
 
   <dependencies>
-    <dependency>
-      <groupId>rubygems</groupId>
-      <artifactId>bundler</artifactId>
-      <version>${bundler.version}</version>
-      <type>gem</type>
-    </dependency>
     <dependency>
       <groupId>rubygems</groupId>
       <artifactId>warbler</artifactId>
@@ -46,6 +40,12 @@
       <version>${jruby.version}</version>
       <type>gem</type>
     </dependency>
+    <dependency>
+      <groupId>rubygems</groupId>
+      <artifactId>jruby-rack</artifactId>
+      <version>${jruby-rack.version}</version>
+      <type>gem</type>
+    </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter</artifactId>
@@ -149,17 +149,11 @@
     <pluginManagement>
       <plugins>
         <plugin>
-          <groupId>org.eclipse.jetty</groupId>
-          <artifactId>jetty-maven-plugin</artifactId>
-          <version>${jetty.version}</version>
+          <groupId>org.eclipse.jetty.${java.ee.version}</groupId>
+          <artifactId>jetty-${java.ee.version}-maven-plugin</artifactId>
           <configuration>
-            <webAppConfig>
-              <contextPath>/</contextPath>
-            </webAppConfig>
             <stopPort>9966</stopPort>
             <stopKey>warbler_stop</stopKey>
-            <scanIntervalSeconds>0</scanIntervalSeconds>
-            <daemon>true</daemon>
             <supportedPackagings>jar</supportedPackagings>
             <systemProperties>
               <systemProperty>
@@ -197,7 +191,7 @@
               <phase>pre-integration-test</phase>
               <goals>
                 <!-- Change to run-war to interactively play with the server without running tests -->
-                <goal>deploy-war</goal>
+                <goal>start-war</goal>
               </goals>
             </execution>
             <execution>
diff --git a/integration/rails7_test/pom.xml b/integration/rails7_test/pom.xml
index 24cf63f8..ae0c9e47 100644
--- a/integration/rails7_test/pom.xml
+++ b/integration/rails7_test/pom.xml
@@ -28,8 +28,8 @@
         </executions>
       </plugin>
       <plugin>
-        <groupId>org.eclipse.jetty</groupId>
-        <artifactId>jetty-maven-plugin</artifactId>
+        <groupId>org.eclipse.jetty.${java.ee.version}</groupId>
+        <artifactId>jetty-${java.ee.version}-maven-plugin</artifactId>
         <executions>
           <execution>
             <id>start-jetty</id>
diff --git a/integration/rails7_test/src/main/ruby/.bundle/config b/integration/rails7_test/src/main/ruby/.bundle/config
new file mode 100644
index 00000000..704b057f
--- /dev/null
+++ b/integration/rails7_test/src/main/ruby/.bundle/config
@@ -0,0 +1,3 @@
+---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
diff --git a/integration/runnable_test/src/main/ruby/.bundle/config b/integration/runnable_test/src/main/ruby/.bundle/config
new file mode 100644
index 00000000..704b057f
--- /dev/null
+++ b/integration/runnable_test/src/main/ruby/.bundle/config
@@ -0,0 +1,3 @@
+---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
diff --git a/integration/runnable_w_bundler_test/src/main/ruby/.bundle/config b/integration/runnable_w_bundler_test/src/main/ruby/.bundle/config
new file mode 100644
index 00000000..704b057f
--- /dev/null
+++ b/integration/runnable_w_bundler_test/src/main/ruby/.bundle/config
@@ -0,0 +1,3 @@
+---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
diff --git a/integration/simple_rack_test/pom.xml b/integration/simple_rack_test/pom.xml
index 41586fde..3a7f1c13 100644
--- a/integration/simple_rack_test/pom.xml
+++ b/integration/simple_rack_test/pom.xml
@@ -24,8 +24,8 @@
         </executions>
       </plugin>
       <plugin>
-        <groupId>org.eclipse.jetty</groupId>
-        <artifactId>jetty-maven-plugin</artifactId>
+        <groupId>org.eclipse.jetty.${java.ee.version}</groupId>
+        <artifactId>jetty-${java.ee.version}-maven-plugin</artifactId>
         <executions>
           <execution>
             <id>start-jetty</id>
diff --git a/integration/simple_rack_test/src/main/ruby/config/warble.rb b/integration/simple_rack_test/src/main/ruby/config/warble.rb
index 09315124..ea2e7fc8 100644
--- a/integration/simple_rack_test/src/main/ruby/config/warble.rb
+++ b/integration/simple_rack_test/src/main/ruby/config/warble.rb
@@ -2,4 +2,5 @@
   config.autodeploy_dir = "../../../target"
   config.jar_name = "simple_rack_test-1.0"
   config.bundler = false
+  config.gems << Gem::Dependency.new("rack", "~> 2.2.0")
 end
diff --git a/spec/rails7_stub/.bundle/config b/spec/rails7_stub/.bundle/config
new file mode 100644
index 00000000..704b057f
--- /dev/null
+++ b/spec/rails7_stub/.bundle/config
@@ -0,0 +1,3 @@
+---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
diff --git a/spec/sample_bundler/.bundle/config b/spec/sample_bundler/.bundle/config
index de114412..386d1f58 100644
--- a/spec/sample_bundler/.bundle/config
+++ b/spec/sample_bundler/.bundle/config
@@ -1,5 +1,6 @@
 ---
+BUNDLE_VERSION: "system"
+BUNDLE_DISABLE_SHARED_GEMS: "true"
 BUNDLE_FROZEN: "true"
 BUNDLE_PATH: "vendor/bundle"
-BUNDLE_DISABLE_SHARED_GEMS: "1"
 BUNDLE_DEPLOYMENT: "false"