diff --git a/.github/workflows/ci-draft.yml b/.github/workflows/ci-draft.yml
index 2484ef6..3441c72 100644
--- a/.github/workflows/ci-draft.yml
+++ b/.github/workflows/ci-draft.yml
@@ -103,7 +103,7 @@ jobs:
     needs: [ Artefact-Version, Push-Draft-OpenAPI-Spec ]
     strategy:
       matrix:
-        java: [ 25 ]
+        java: [ 21 ]
 
     steps:
       - name: Checkout source code
diff --git a/.github/workflows/ci-released.yml b/.github/workflows/ci-released.yml
index b649728..69283eb 100644
--- a/.github/workflows/ci-released.yml
+++ b/.github/workflows/ci-released.yml
@@ -66,7 +66,7 @@ jobs:
     needs: [ Artefact-Version, Push-Release-OpenAPI-Spec ]
     strategy:
       matrix:
-        java: [ 25 ]
+        java: [ 21 ]
 
     steps:
       - name: Checkout source code
diff --git a/.github/workflows/code-analysis.yml b/.github/workflows/code-analysis.yml
index c33adf3..86b6f38 100644
--- a/.github/workflows/code-analysis.yml
+++ b/.github/workflows/code-analysis.yml
@@ -17,7 +17,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
-          java-version: '25'
+          java-version: '21'
 
       - uses: pmd/pmd-github-action@v2
         id: pmd
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index 17c0390..4b7f491 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -40,7 +40,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: 'temurin'
-          java-version: '25'
+          java-version: '21'
 
       - name: Set up Gradle
         uses: gradle/actions/setup-gradle@v5
diff --git a/gradle/java.gradle b/gradle/java.gradle
index d7e4cdf..11abad8 100644
--- a/gradle/java.gradle
+++ b/gradle/java.gradle
@@ -1,6 +1,6 @@
 java {
   toolchain {
-    languageVersion = JavaLanguageVersion.of(25)
+    languageVersion = JavaLanguageVersion.of(21)
   }
 }