diff --git a/.github/workflows/ci-container.yml b/.github/workflows/ci-container.yml
index 21b41b67390..24ae8af927e 100644
--- a/.github/workflows/ci-container.yml
+++ b/.github/workflows/ci-container.yml
@@ -11,11 +11,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 1
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
           distribution: liberica
-          java-version: '17'
+          java-version: '21'
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
         with:
@@ -36,7 +36,7 @@ jobs:
         # Hack around #5450
       - name: pull base image
         run: |
-          docker pull --platform linux/amd64 --platform linux/arm64 gcr.io/distroless/java17-debian12:latest      
+          docker pull --platform linux/amd64 --platform linux/arm64 gcr.io/distroless/java21-debian12:latest      
       - name: Build images
         run: mvn -V -B -q -Pdocker -DskipTests -Ddependency-check.skip=true -P !mac-dmg-on-unix,!installer,!concurrency-stress-tests,!micro-benchmarks,skip-build-dist-archives clean package
       - name: Check local images
diff --git a/.github/workflows/ci-snapshots.yml b/.github/workflows/ci-snapshots.yml
index 965472d7461..f88d0c5727a 100644
--- a/.github/workflows/ci-snapshots.yml
+++ b/.github/workflows/ci-snapshots.yml
@@ -15,11 +15,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 1
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
           distribution: liberica
-          java-version: '17'
+          java-version: '21'
           server-id: github
           settings-path: ${{ github.workspace }}
       - name: Cache Maven packages
diff --git a/.github/workflows/ci-test.yml b/.github/workflows/ci-test.yml
index 66a053a3267..9eab3f6f32d 100644
--- a/.github/workflows/ci-test.yml
+++ b/.github/workflows/ci-test.yml
@@ -4,7 +4,7 @@ permissions:
   contents: read
 env:
   MAVEN_OPTS: -DtrimStackTrace=false -D'maven.resolver.transport=wagon'
-  DEV_JDK: '17'
+  DEV_JDK: '21'
 jobs:
   license:
     name: License check
@@ -40,7 +40,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
-        jvm: ['17', '21']
+        jvm: ['21']
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
diff --git a/.github/workflows/ci-xqts.yml b/.github/workflows/ci-xqts.yml
index f326aec0910..883e50bf4ae 100644
--- a/.github/workflows/ci-xqts.yml
+++ b/.github/workflows/ci-xqts.yml
@@ -9,11 +9,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
           distribution: liberica
-          java-version: '17'
+          java-version: '21'
       - name: Cache Maven packages
         uses: actions/cache@v4
         with:
diff --git a/.github/workflows/sonarcloud.yml b/.github/workflows/sonarcloud.yml
index 1bc41d15196..cfd886ece17 100644
--- a/.github/workflows/sonarcloud.yml
+++ b/.github/workflows/sonarcloud.yml
@@ -14,11 +14,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
           distribution: liberica
-          java-version: 17
+          java-version: 21
       - name: Cache SonarCloud packages
         uses: actions/cache@v4
         with:
diff --git a/BUILD.md b/BUILD.md
index 8e1c8374f7e..ef869f3b817 100644
--- a/BUILD.md
+++ b/BUILD.md
@@ -1,7 +1,7 @@
 Building eXist-db from Source
 --------------------------
 
-eXist-db itself is written in Java 17. The build system is [Apache Maven](http://maven.apache.org/). If you're not familiar with Git, we recommend [this excellent online interactive tutorial](http://try.github.io).
+eXist-db itself is written in and qualified with Java 21. The build system is [Apache Maven](http://maven.apache.org/). If you're not familiar with Git, we recommend [this excellent online interactive tutorial](http://try.github.io).
 
 To build eXist-db:
 
diff --git a/README.md b/README.md
index 4d9c4ad1cbc..c1a50b7adfc 100644
--- a/README.md
+++ b/README.md
@@ -6,11 +6,11 @@
 
 ## eXist-db Native XML Database
 
-[![Build Status](https://github.com/eXist-db/exist/actions/workflows/ci-build.yml/badge.svg?branch=develop)](https://github.com/eXist-db/exist/actions/workflows/ci-build.yml)
+[![Build Status](https://github.com/eXist-db/exist/actions/workflows/ci-test.yml/badge.svg?branch=develop)](https://github.com/eXist-db/exist/actions/workflows/ci-build.yml)
 [![Coverage Status](https://coveralls.io/repos/github/eXist-db/exist/badge.svg?branch=develop)](https://coveralls.io/github/eXist-db/exist?branch=develop)
 [![Codacy Badge](https://app.codacy.com/project/badge/Grade/ae1c8a7eb1164e919b0ac3c8588560c6)](https://www.codacy.com/gh/eXist-db/exist/dashboard?utm_source=github.com&utm_medium=referral&utm_content=eXist-db/exist&utm_campaign=Badge_Grade)
 [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=eXist-db_exist&metric=alert_status)](https://sonarcloud.io/summary/new_code?id=eXist-db_exist)
-[![Java 17](https://img.shields.io/badge/java-17-blue.svg)](https://adoptopenjdk.net/)
+[![Java 21](https://img.shields.io/badge/java-21-blue.svg)](https://adoptopenjdk.net/)
 [![License](https://img.shields.io/badge/license-LGPL%202.1-blue.svg)](https://www.gnu.org/licenses/lgpl-2.1.html)
 [![Download](https://img.shields.io/github/v/release/eXist-db/exist.svg)](https://github.com/eXist-db/exist/releases/)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.exist-db/exist/badge.svg)](https://search.maven.org/search?q=g:org.exist-db)
diff --git a/exist-core-jmh/pom.xml b/exist-core-jmh/pom.xml
index b67ce915781..2516466af64 100644
--- a/exist-core-jmh/pom.xml
+++ b/exist-core-jmh/pom.xml
@@ -121,11 +121,6 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <compilerVersion>${project.build.target}</compilerVersion>
-                    <source>${project.build.source}</source>
-                    <target>${project.build.target}</target>
-                </configuration>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
diff --git a/exist-core/pom.xml b/exist-core/pom.xml
index a9abcc918d0..b50fb2b8ba5 100644
--- a/exist-core/pom.xml
+++ b/exist-core/pom.xml
@@ -1094,6 +1094,7 @@ The BaseX Team. The original license statement is also included below.]]></pream
             </plugin>
 
             <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <executions>
                     <execution>
@@ -1135,9 +1136,9 @@ The BaseX Team. The original license statement is also included below.]]></pream
                         <configuration>
                             <forceAjcCompile>true</forceAjcCompile>  <!-- Required, otherwise the Aspects are not re-compiled when the src/main/java is recompiled for the test phase -->
                             <showWeaveInfo>true</showWeaveInfo>
-                            <complianceLevel>${project.build.source}</complianceLevel>
-                            <source>${project.build.source}</source>
-                            <target>${project.build.target}</target>
+                            <complianceLevel>${maven.compiler.release}</complianceLevel>
+                            <source>${maven.compiler.source}</source>
+                            <target>${maven.compiler.target}</target>
                             <!-- sources>
                                 <source>
                                     <basedir>${project.build.sourceDirectory}</basedir>
diff --git a/exist-docker/src/main/resources-filtered/Dockerfile b/exist-docker/src/main/resources-filtered/Dockerfile
index 72cbcda71eb..0d6e9ded98b 100644
--- a/exist-docker/src/main/resources-filtered/Dockerfile
+++ b/exist-docker/src/main/resources-filtered/Dockerfile
@@ -20,7 +20,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #
 
-FROM gcr.io/distroless/java17-debian12:latest
+FROM gcr.io/distroless/java21-debian12:latest
 
 # Copy eXist-db
 COPY LICENSE /exist/LICENSE
diff --git a/exist-docker/src/main/resources-filtered/Dockerfile-DEBUG b/exist-docker/src/main/resources-filtered/Dockerfile-DEBUG
index dce96d14545..21db2e06d17 100644
--- a/exist-docker/src/main/resources-filtered/Dockerfile-DEBUG
+++ b/exist-docker/src/main/resources-filtered/Dockerfile-DEBUG
@@ -20,10 +20,8 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #
 
-# Use JDK 17 in Debian as our production image gcr.io/distroless/java is based on Debian with just a JRE)
-FROM debian:bookworm-slim
+FROM openjdk:21-jdk-slim-bullseye
 RUN apt-get update && apt-get -y dist-upgrade
-RUN apt-get install -y openjdk-17-jdk-headless
 RUN apt-get install -y expat fontconfig     # Install tools required by FOP
 
 # Copy eXist-db
diff --git a/exist-docker/src/main/resources-filtered/README.md b/exist-docker/src/main/resources-filtered/README.md
index 69ea75b8ae3..fd1d3d42168 100644
--- a/exist-docker/src/main/resources-filtered/README.md
+++ b/exist-docker/src/main/resources-filtered/README.md
@@ -17,7 +17,7 @@ The images are based on Google Cloud Platform's ["Distroless" Docker Images](htt
 *   [Docker](https://www.docker.com): `18-stable`
 ### For building
 *   [maven](https://maven.apache.org/): `^3.6.0`
-*   [java](https://www.java.com/): `17`
+*   [java](https://www.java.com/): `21`
 *   [bats](https://github.com/bats-core/bats-core): `^1.1.0` (for testing)
 
 ## How to use
diff --git a/exist-installer/src/main/izpack/install.xml b/exist-installer/src/main/izpack/install.xml
index f781da1cc63..58f31e4669b 100644
--- a/exist-installer/src/main/izpack/install.xml
+++ b/exist-installer/src/main/izpack/install.xml
@@ -38,7 +38,7 @@
         <authors>
             <author name="${izpack.installation.info.author.name}" email="${izpack.installation.info.author.email}"/>
         </authors>
-        <javaversion>@{project.build.target}</javaversion>
+        <javaversion>@{maven.compiler.release}</javaversion>
         <requiresjdk>no</requiresjdk>
         <run-privileged condition="izpack.windowsinstall"/>
         <pack-compression-format>xz</pack-compression-format>
diff --git a/exist-parent/pom.xml b/exist-parent/pom.xml
index 20eeec4da12..889ed51bf6c 100644
--- a/exist-parent/pom.xml
+++ b/exist-parent/pom.xml
@@ -92,8 +92,9 @@
     </mailingLists>
 
     <properties>
-        <project.build.source>17</project.build.source>
-        <project.build.target>17</project.build.target>
+        <maven.compiler.release>21</maven.compiler.release>
+        <maven.compiler.source>${maven.compiler.release}</maven.compiler.source>
+        <maven.compiler.target>${maven.compiler.release}</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
         <project.copyright.name>The eXist-db Authors</project.copyright.name>
@@ -693,10 +694,8 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.13.0</version>
+                    <version>3.14.0</version>
                     <configuration>
-                        <source>${project.build.source}</source>
-                        <target>${project.build.target}</target>
                         <encoding>${project.build.sourceEncoding}</encoding>
                     </configuration>
                 </plugin>
@@ -753,7 +752,7 @@
                     <artifactId>maven-javadoc-plugin</artifactId>
                     <version>3.11.2</version>
                     <configuration>
-                        <source>${project.build.source}</source>
+                        <source>${maven.compiler.release}</source>
                         <archive>
                             <manifest>
                                 <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
@@ -977,6 +976,31 @@
         </pluginManagement>
 
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-enforcer-plugin</artifactId>
+                <version>3.5.0</version>
+                <executions>
+                    <execution>
+                        <id>enforce-java</id>
+                        <goals>
+                            <goal>enforce</goal>
+                        </goals>
+                        <configuration>
+                            <rules>
+                                <requireJavaVersion>
+                                    <version>${maven.compiler.target}</version>
+                                    <message>eXist-db requires (at least) OpenJDK ${maven.compiler.target} to build and run.</message>
+                                </requireJavaVersion>
+                                <requireMavenVersion>
+                                    <message>Modern plugins require atleast maven 3.6.3.</message>
+                                    <version>3.6.3</version>
+                                </requireMavenVersion>
+                            </rules>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>com.mycila</groupId>
                 <artifactId>license-maven-plugin</artifactId>