diff --git a/.github/workflows/gradle.yml b/.github/workflows/gradle.yml
index aea6a8e28..88f81c1b9 100644
--- a/.github/workflows/gradle.yml
+++ b/.github/workflows/gradle.yml
@@ -23,14 +23,18 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v7
 
-      - name: Set up JDK 8
+      # Gradle 9 runs only on Java 17+, so 17 is listed last and becomes JAVA_HOME. The SDK's
+      # tests still run on Java 8, its floor, through the toolchain sdk-java/build.gradle selects.
+      - name: Set up JDK 8 and 17
         uses: actions/setup-java@v6
         with:
-          java-version: '8'
+          java-version: |
+            8
+            17
           distribution: 'corretto'
 
       - name: Build and Test with Gradle
-        run: ./gradlew build
+        run: ./gradlew build -PtestJavaVersion=8 -Porg.gradle.java.installations.fromEnv=JAVA_HOME_8_X64
 
       - name: Publish Test Results
         uses: EnricoMi/publish-unit-test-result-action@v2
diff --git a/app-java/build.gradle b/app-java/build.gradle
index 1de384cec..bc19c7481 100644
--- a/app-java/build.gradle
+++ b/app-java/build.gradle
@@ -16,4 +16,6 @@ dependencies {
   //implementation "ly.count.sdk:java:${CLY_VERSION}"
 }
 
-mainClassName = 'ly.count.java.demo.ReproduceIssue264'
+application {
+  mainClass = 'ly.count.java.demo.ReproduceIssue264'
+}
diff --git a/build.gradle b/build.gradle
index dea50f888..b7ab9359f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -157,7 +157,7 @@ ext.countFailedTests = { module ->
   int failed = 0
   resultsDir.listFiles({ file -> file.name.endsWith('.xml') } as FileFilter)?.each { file ->
     try {
-      def suite = new XmlParser(false, false).parse(file)
+      def suite = new groovy.xml.XmlParser(false, false).parse(file)
       failed += (suite.@failures as int) + (suite.@errors as int)
     } catch (Exception ignored) {
       // An unreadable result file is not worth failing the summary over.
@@ -173,7 +173,7 @@ ext.countFailedTests = { module ->
  * build depend on the network, so external entities are switched off.
  */
 ext.readCounters = { File report ->
-  def parser = new XmlParser(false, false)
+  def parser = new groovy.xml.XmlParser(false, false)
   parser.setFeature('http://apache.org/xml/features/disallow-doctype-decl', false)
   parser.setFeature('http://apache.org/xml/features/nonvalidating/load-external-dtd', false)
 
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 1b33c55ba..9fa7f2882 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 4f5eb9dcc..2a66ec2c7 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.8.2-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/gradlew b/gradlew
index 23d15a936..249efbb03 100755
--- a/gradlew
+++ b/gradlew
@@ -1,7 +1,7 @@
 #!/bin/sh
 
 #
-# Copyright © 2015-2021 the original authors.
+# Copyright © 2015 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -20,7 +20,7 @@
 
 ##############################################################################
 #
-#   Gradle start up script for POSIX generated by Gradle.
+#   gradlew start up script for POSIX generated by Gradle.
 #
 #   Important for running:
 #
@@ -29,7 +29,7 @@
 #       bash, then to run this script, type that shell name before the whole
 #       command line, like:
 #
-#           ksh Gradle
+#           ksh gradlew
 #
 #       Busybox and similar reduced shells will NOT work, because this script
 #       requires all of these POSIX shell features:
@@ -57,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/3d91ce3b8caaf77ad09f381f43615b715b53f72c/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -114,7 +114,6 @@ case "$( uname )" in                #(
   NONSTOP* )        nonstop=true ;;
 esac
 
-CLASSPATH="\\\"\\\""
 
 
 # Determine the Java command to use to start the JVM.
@@ -172,7 +171,6 @@ fi
 # For Cygwin or MSYS, switch paths to Windows format before running java
 if "$cygwin" || "$msys" ; then
     APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
-    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
     JAVACMD=$( cygpath --unix "$JAVACMD" )
 
@@ -212,7 +210,6 @@ DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
-        -classpath "$CLASSPATH" \
         -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \
         "$@"
 
diff --git a/gradlew.bat b/gradlew.bat
index 5eed7ee84..03754c4c3 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -19,12 +19,39 @@
 @if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
-@rem  Gradle startup script for Windows
+@rem  gradlew startup script for Windows
 @rem
 @rem ##########################################################################
 
-@rem Set local scope for the variables with windows NT shell
-if "%OS%"=="Windows_NT" setlocal
+@rem Set local scope for the variables, and ensure extensions are enabled
+setlocal EnableExtensions
+
+@rem Catch executions from older scripts and ensure they exit cleanly.
+@rem This can be removed once we can be reasonably confident that few people
+@rem will be migrating directly to this new wrapper.
+goto afterSafetyNet
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
+goto exitWithErrorLevel
+:afterSafetyNet
 
 set DIRNAME=%~dp0
 if "%DIRNAME%"=="" set DIRNAME=.
@@ -45,13 +72,14 @@ set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
 if %ERRORLEVEL% equ 0 goto execute
 
-echo. 1>&2
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
-echo. 1>&2
-echo Please set the JAVA_HOME variable in your environment to match the 1>&2
-echo location of your Java installation. 1>&2
+1>&2 echo.
+1>&2 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+1>&2 echo.
+1>&2 echo Please set the JAVA_HOME variable in your environment to match the
+1>&2 echo location of your Java installation.
 
-goto fail
+"%COMSPEC%" /c exit 1
+goto exitWithErrorLevel
 
 :findJavaFromJavaHome
 set JAVA_HOME=%JAVA_HOME:"=%
@@ -59,36 +87,26 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo. 1>&2
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
-echo. 1>&2
-echo Please set the JAVA_HOME variable in your environment to match the 1>&2
-echo location of your Java installation. 1>&2
+1>&2 echo.
+1>&2 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+1>&2 echo.
+1>&2 echo Please set the JAVA_HOME variable in your environment to match the
+1>&2 echo location of your Java installation.
 
-goto fail
+"%COMSPEC%" /c exit 1
+goto exitWithErrorLevel
 
 :execute
 @rem Setup the command line
 
-set CLASSPATH=
 
 
-@rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %*
+@rem Execute gradlew
+@rem endlocal doesn't take effect until after the line is parsed and variables are expanded
+@rem which allows us to clear the local environment before executing the java command
+endlocal & "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %* & call :exitWithErrorLevel & goto exitWithErrorLevel
 
-:end
-@rem End local scope for the variables with windows NT shell
-if %ERRORLEVEL% equ 0 goto mainEnd
-
-:fail
-rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
-rem the _cmd.exe /c_ return code!
-set EXIT_CODE=%ERRORLEVEL%
-if %EXIT_CODE% equ 0 set EXIT_CODE=1
-if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
-exit /b %EXIT_CODE%
-
-:mainEnd
-if "%OS%"=="Windows_NT" endlocal
-
-:omega
+@rem This label must not be changed. We rely on old scripts being able to jump to this point.
+:exitWithErrorLevel
+@rem Use "%COMSPEC%" /c exit to allow operators to work properly in scripts
+"%COMSPEC%" /c exit %ERRORLEVEL%
diff --git a/sdk-java/build.gradle b/sdk-java/build.gradle
index ecd2a8b57..02391c4cc 100644
--- a/sdk-java/build.gradle
+++ b/sdk-java/build.gradle
@@ -17,6 +17,16 @@ if (JavaVersion.current().isJava9Compatible()) {
   }
 }
 
+// Gradle itself needs Java 17, so CI passes -PtestJavaVersion=8 to run the tests on the SDK's Java 8 floor.
+def testJavaVersion = findProperty('testJavaVersion')
+if (testJavaVersion) {
+  tasks.named('test') {
+    javaLauncher = javaToolchains.launcherFor {
+      languageVersion = JavaLanguageVersion.of(testJavaVersion.toString())
+    }
+  }
+}
+
 dependencies {
   implementation 'org.json:json:20260814'
   implementation 'com.google.code.findbugs:jsr305:3.0.2'