diff --git a/.github/workflows/samples-kotlin-server.yaml b/.github/workflows/samples-kotlin-server.yaml
index e50e501fcd75..fd083eddab34 100644
--- a/.github/workflows/samples-kotlin-server.yaml
+++ b/.github/workflows/samples-kotlin-server.yaml
@@ -59,7 +59,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
-          java-version: 8
+          java-version: 11
       - name: Cache maven dependencies
         uses: actions/cache@v4
         env:
diff --git a/modules/openapi-generator/src/main/resources/kotlin-server/libraries/jaxrs-spec/build.gradle.mustache b/modules/openapi-generator/src/main/resources/kotlin-server/libraries/jaxrs-spec/build.gradle.mustache
index 068055e17ad5..3c44e0286e33 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-server/libraries/jaxrs-spec/build.gradle.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-server/libraries/jaxrs-spec/build.gradle.mustache
@@ -37,14 +37,14 @@ apply plugin: "java"
 apply plugin: "kotlin"
 apply plugin: "application"
 
-sourceCompatibility = 1.8
+sourceCompatibility = 11
 
 compileKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 repositories {
diff --git a/samples/server/others/kotlin-server/jaxrs-spec-array-response/build.gradle b/samples/server/others/kotlin-server/jaxrs-spec-array-response/build.gradle
index 7184bbeb236c..83d1697e1aa6 100644
--- a/samples/server/others/kotlin-server/jaxrs-spec-array-response/build.gradle
+++ b/samples/server/others/kotlin-server/jaxrs-spec-array-response/build.gradle
@@ -25,14 +25,14 @@ apply plugin: "java"
 apply plugin: "kotlin"
 apply plugin: "application"
 
-sourceCompatibility = 1.8
+sourceCompatibility = 11
 
 compileKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 repositories {
diff --git a/samples/server/others/kotlin-server/jaxrs-spec/build.gradle b/samples/server/others/kotlin-server/jaxrs-spec/build.gradle
index 804d53562cb1..4b2e731a69b8 100644
--- a/samples/server/others/kotlin-server/jaxrs-spec/build.gradle
+++ b/samples/server/others/kotlin-server/jaxrs-spec/build.gradle
@@ -25,14 +25,14 @@ apply plugin: "java"
 apply plugin: "kotlin"
 apply plugin: "application"
 
-sourceCompatibility = 1.8
+sourceCompatibility = 11
 
 compileKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 repositories {
diff --git a/samples/server/petstore/kotlin-server/jaxrs-spec-mutiny/build.gradle b/samples/server/petstore/kotlin-server/jaxrs-spec-mutiny/build.gradle
index f78fee560a9b..a5be14d58d84 100644
--- a/samples/server/petstore/kotlin-server/jaxrs-spec-mutiny/build.gradle
+++ b/samples/server/petstore/kotlin-server/jaxrs-spec-mutiny/build.gradle
@@ -26,14 +26,14 @@ apply plugin: "java"
 apply plugin: "kotlin"
 apply plugin: "application"
 
-sourceCompatibility = 1.8
+sourceCompatibility = 11
 
 compileKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 repositories {
diff --git a/samples/server/petstore/kotlin-server/jaxrs-spec/build.gradle b/samples/server/petstore/kotlin-server/jaxrs-spec/build.gradle
index 804d53562cb1..4b2e731a69b8 100644
--- a/samples/server/petstore/kotlin-server/jaxrs-spec/build.gradle
+++ b/samples/server/petstore/kotlin-server/jaxrs-spec/build.gradle
@@ -25,14 +25,14 @@ apply plugin: "java"
 apply plugin: "kotlin"
 apply plugin: "application"
 
-sourceCompatibility = 1.8
+sourceCompatibility = 11
 
 compileKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = "1.8"
+    kotlinOptions.jvmTarget = "11"
 }
 
 repositories {