diff --git a/buildSrc/build.gradle.kts b/buildSrc/build.gradle.kts
index 144f9565c73..241cdee77bd 100644
--- a/buildSrc/build.gradle.kts
+++ b/buildSrc/build.gradle.kts
@@ -43,7 +43,4 @@ dependencies {
 
   implementation("gradle.plugin.io.morethan.jmhreport:gradle-jmh-report:0.9.6")
   implementation("me.champeau.jmh:jmh-gradle-plugin:0.7.3")
-
-  // earlier versions aren't compatible with Gradle 8.1.1
-  implementation("org.springframework.boot:spring-boot-gradle-plugin:2.5.12")
 }
diff --git a/buildSrc/src/main/kotlin/ai.smoke-test-jar.gradle.kts b/buildSrc/src/main/kotlin/ai.smoke-test-jar.gradle.kts
index bf6a7dcb5ac..62057c978f8 100644
--- a/buildSrc/src/main/kotlin/ai.smoke-test-jar.gradle.kts
+++ b/buildSrc/src/main/kotlin/ai.smoke-test-jar.gradle.kts
@@ -1,11 +1,43 @@
+import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
+import com.github.jengelman.gradle.plugins.shadow.transformers.AppendingTransformer
 import com.microsoft.applicationinsights.gradle.AiSmokeTestExtension
 
 plugins {
   id("ai.smoke-test")
-  id("org.springframework.boot")
+  id("com.gradleup.shadow")
 }
 
 val aiSmokeTest = extensions.getByType(AiSmokeTestExtension::class)
 
-aiSmokeTest.testAppArtifactDir.set(tasks.bootJar.flatMap { it.destinationDirectory })
-aiSmokeTest.testAppArtifactFilename.set(tasks.bootJar.flatMap { it.archiveFileName })
+// Create a fat JAR using Shadow instead of Spring Boot plugin for Gradle 9 compatibility
+// Spring Boot 2.x doesn't support Gradle 9, and Spring Boot 3.x requires Java 17+
+// Shadow creates a simple fat JAR that works with Java 8
+tasks.named<ShadowJar>("shadowJar") {
+  archiveClassifier.set("")
+  mergeServiceFiles()
+  
+  // Append spring.factories files from all dependencies
+  // This is required for Spring Boot auto-configuration to work
+  append("META-INF/spring.factories")
+  
+  // Set main class - can be overridden by individual projects via mainClassName property
+  manifest {
+    val mainClass = if (project.hasProperty("mainClassName")) {
+      project.property("mainClassName") as String
+    } else {
+      // Default main class for most smoke test apps
+      "com.microsoft.applicationinsights.smoketestapp.SpringBootApp"
+    }
+    attributes["Main-Class"] = mainClass
+  }
+}
+
+// Make jar task depend on shadowJar and use the shadow JAR output
+// This prevents the regular jar task from overwriting the fat JAR
+tasks.named<Jar>("jar") {
+  dependsOn(tasks.shadowJar)
+  enabled = false
+}
+
+aiSmokeTest.testAppArtifactDir.set(tasks.shadowJar.flatMap { it.destinationDirectory })
+aiSmokeTest.testAppArtifactFilename.set(tasks.shadowJar.flatMap { it.archiveFileName })
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index d4081da476b..19a6bdeb848 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-8.14.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.3.0-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/smoke-tests/apps/JettyNativeHandler/build.gradle.kts b/smoke-tests/apps/JettyNativeHandler/build.gradle.kts
index 2bb4f96b5b8..7b2c8cb225f 100644
--- a/smoke-tests/apps/JettyNativeHandler/build.gradle.kts
+++ b/smoke-tests/apps/JettyNativeHandler/build.gradle.kts
@@ -2,6 +2,9 @@ plugins {
   id("ai.smoke-test-jar")
 }
 
+// Override default main class
+ext.set("mainClassName", "com.microsoft.applicationinsights.smoketestapp.JettyNativeHandlerApp")
+
 dependencies {
   implementation("org.springframework.boot:spring-boot-starter:2.5.12")
 
diff --git a/smoke-tests/apps/ReadOnly/build.gradle.kts b/smoke-tests/apps/ReadOnly/build.gradle.kts
index 29d8040b549..b2b99c406ac 100644
--- a/smoke-tests/apps/ReadOnly/build.gradle.kts
+++ b/smoke-tests/apps/ReadOnly/build.gradle.kts
@@ -1,3 +1,6 @@
 plugins {
   id("ai.smoke-test-jar")
 }
+
+// Override default main class
+ext.set("mainClassName", "com.microsoft.applicationinsights.smoketestapp.App")
diff --git a/smoke-tests/apps/gRPC/build.gradle.kts b/smoke-tests/apps/gRPC/build.gradle.kts
index eae03a2ecef..8281fb5022c 100644
--- a/smoke-tests/apps/gRPC/build.gradle.kts
+++ b/smoke-tests/apps/gRPC/build.gradle.kts
@@ -2,7 +2,7 @@ import com.google.protobuf.gradle.*
 
 plugins {
   id("ai.smoke-test-jar")
-  id("com.google.protobuf") version "0.8.19"
+  id("com.google.protobuf") version "0.9.6"
 }
 
 val grpcVersion = "1.26.0" // first version with support for arm64