diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index ac7d6128ffc..020100e9305 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -35,8 +35,7 @@ jobs:
       DV_ACCESS_TOKEN: ${{ startsWith(github.ref_name, 'release/') && '' || secrets.GE_ACCESS_TOKEN }}
     with:
       java-version: |
-        8
-        17
+        21
       site-enabled: true
       reproducibility-check-enabled: ${{ startsWith(github.ref_name, 'release/') }}
       develocity-enabled: ${{ ! startsWith(github.ref_name, 'release/') }}
diff --git a/.java-version b/.java-version
index 98d9bcb75a6..aabe6ec3909 100644
--- a/.java-version
+++ b/.java-version
@@ -1 +1 @@
-17
+21
diff --git a/log4j-osgi-test/pom.xml b/log4j-osgi-test/pom.xml
index a4f3d911797..e85367fc79c 100644
--- a/log4j-osgi-test/pom.xml
+++ b/log4j-osgi-test/pom.xml
@@ -46,6 +46,11 @@
   </properties>
 
   <dependencies>
+    <dependency>
+      <groupId>org.ow2.asm</groupId>
+      <artifactId>asm</artifactId>
+      <version>9.6</version>
+    </dependency>
     <dependency>
       <groupId>javax.inject</groupId>
       <artifactId>javax.inject</artifactId>
diff --git a/pom.xml b/pom.xml
index 03760b9eb0a..a863735a38e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -305,6 +305,7 @@
 
   <properties>
 
+    <minimalJavaBuildVersion>[21,22)</minimalJavaBuildVersion>
     <!-- project version -->
     <revision>2.25.0-SNAPSHOT</revision>
     <!-- Versions used on the site: no snapshots! -->
@@ -351,7 +352,7 @@
     <site-je.version>18.3.12</site-je.version>
     <site-jeromq.version>0.6.0</site-jeromq.version>
     <site-kafka.version>3.8.0</site-kafka.version>
-    <site-logback.version>1.5.5</site-logback.version>
+    <site-logback.version>1.3.14</site-logback.version>
     <site-slf4j.version>2.0.16</site-slf4j.version>
 
     <!-- =====================================================
@@ -549,9 +550,47 @@
         <version>${project.version}</version>
       </dependency>
 
+      <dependency>
+        <groupId>org.ow2.asm</groupId>
+        <artifactId>asm</artifactId>
+        <version>9.6</version>
+      </dependency>
+
+      <dependency>
+        <groupId>org.ow2.asm</groupId>
+        <artifactId>asm-commons</artifactId>
+        <version>9.6</version>
+      </dependency>
+
+      <dependency>
+        <groupId>org.ow2.asm</groupId>
+        <artifactId>asm-tree</artifactId>
+        <version>9.6</version>
+      </dependency>
+
+      <dependency>
+        <groupId>org.ow2.asm</groupId>
+        <artifactId>asm-util</artifactId>
+        <version>9.6</version>
+      </dependency>
+
+      <dependency>
+        <groupId>org.ow2.asm</groupId>
+        <artifactId>asm-analysis</artifactId>
+        <version>9.6</version>
+      </dependency>
+
     </dependencies>
   </dependencyManagement>
 
+  <dependencies>
+    <dependency>
+      <groupId>org.openjdk.nashorn</groupId>
+      <artifactId>nashorn-core</artifactId>
+      <version>15.4</version>
+    </dependency>
+  </dependencies>
+
   <build>
 
     <plugins>
@@ -618,8 +657,14 @@
           <forkCount>1C</forkCount>
           <reuseForks>false</reuseForks>
           <runOrder>random</runOrder>
+          <argLine>--add-opens java.base/java.lang=ALL-UNNAMED
+            --add-opens java.base/java.util=ALL-UNNAMED
+            --add-opens java.base/java.net=ALL-UNNAMED
+            --add-opens java.base/java.io=ALL-UNNAMED
+            --add-opens java.base/sun.reflect=ALL-UNNAMED</argLine>
           <systemPropertyVariables>
             <java.awt.headless>true</java.awt.headless>
+            <pax.exam.waitTimeout>600000</pax.exam.waitTimeout>
           </systemPropertyVariables>
         </configuration>
       </plugin>
@@ -1007,7 +1052,7 @@
                 <id>default-test</id>
                 <configuration>
                   <jdkToolchain>
-                    <version>[1.8, 9)</version>
+                    <version>21</version>
                   </jdkToolchain>
                 </configuration>
               </execution>
diff --git a/src/site/antora/antora.yml b/src/site/antora/antora.yml
index 21652d7e98f..dff16e96365 100644
--- a/src/site/antora/antora.yml
+++ b/src/site/antora/antora.yml
@@ -44,8 +44,8 @@ asciidoc:
     project-github-url: "https://github.com/apache/logging-log4j2/tree/2.x"
     project-name: "Log4j"
     project-id: "log4j"
-    java-target-version: "8"
-    java-compiler-version: "[17,18)"
+    java-target-version: "21"
+    java-compiler-version: "21"
     log4j-kubernetes-url: "https://github.com/fabric8io/kubernetes-client/blob/main/doc/KubernetesLog4j.md"
     logback-url: "https://logback.qos.ch"
     logging-services-url: "https://logging.apache.org"