diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86efe6c76..4115efb74 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 ### Changed
 - Jenkins master and agent maintenance. Add Rhel9 variant and make it default ([#1361](https://github.com/opendevstack/ods-core/pull/1361))
 - Update tailor to 1.4.0 ([#1373](https://github.com/opendevstack/ods-core/pull/1373))
+- Update Jenkins java version to jdk 21 ([#1374](https://github.com/opendevstack/ods-core/pull/1374))
 
 ### Fixed
 
diff --git a/jenkins/agent-base/Dockerfile.ubi8 b/jenkins/agent-base/Dockerfile.ubi8
index 6b6a21569..ccea18131 100644
--- a/jenkins/agent-base/Dockerfile.ubi8
+++ b/jenkins/agent-base/Dockerfile.ubi8
@@ -40,9 +40,9 @@ RUN chmod +x /usr/local/bin/use-j*.sh && \
     chmod ugo+s /usr/local/bin/use-j*.sh && \
     sh -c 'chmod ugo+s $(which alternatives)' && \
     ls -la /usr/local/bin/use-j*.sh && \
-    echo "--- STARTS JDK 17 TESTS ---" && \
-    use-j17.sh && \
-    echo "--- ENDS JDK 17 TESTS ---"
+    echo "--- STARTS JDK 21 TESTS ---" && \
+    use-j21.sh && \
+    echo "--- ENDS JDK 21 TESTS ---"
 
 COPY ./import_certs.sh /usr/local/bin/import_certs.sh
 COPY ./fix_java_certs_permissions.sh /usr/local/bin/fix_java_certs_permissions.sh
diff --git a/jenkins/agent-base/Dockerfile.ubi9 b/jenkins/agent-base/Dockerfile.ubi9
index 7805c5e73..2f633c34d 100644
--- a/jenkins/agent-base/Dockerfile.ubi9
+++ b/jenkins/agent-base/Dockerfile.ubi9
@@ -40,9 +40,9 @@ RUN chmod +x /usr/local/bin/use-j*.sh && \
     chmod ugo+s /usr/local/bin/use-j*.sh && \
     sh -c 'chmod ugo+s $(which alternatives)' && \
     ls -la /usr/local/bin/use-j*.sh && \
-    echo "--- STARTS JDK 17 TESTS ---" && \
-    use-j17.sh && \
-    echo "--- ENDS JDK 17 TESTS ---"
+    echo "--- STARTS JDK 21 TESTS ---" && \
+    source use-j21.sh && \
+    echo "--- ENDS JDK 21 TESTS ---"
 
 COPY ./import_certs.sh /usr/local/bin/import_certs.sh
 COPY ./fix_java_certs_permissions.sh /usr/local/bin/fix_java_certs_permissions.sh
diff --git a/jenkins/agent-base/ensure_java_jre_is_adequate.sh b/jenkins/agent-base/ensure_java_jre_is_adequate.sh
index 0ce1a12a0..abf6bf715 100755
--- a/jenkins/agent-base/ensure_java_jre_is_adequate.sh
+++ b/jenkins/agent-base/ensure_java_jre_is_adequate.sh
@@ -3,8 +3,8 @@ set -eu -o pipefail
 
 ME="$(basename $0)"
 JAVA_INSTALLED_PKGS_LOGS="/tmp/java_installed_pkgs.log"
-JAVA_17_INSTALLED_PKGS_LOGS="/tmp/java_17_installed_pkgs.log"
-rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_17_INSTALLED_PKGS_LOGS}
+JAVA_TARGET_INSTALLED_PKGS_LOGS="/tmp/java_target_installed_pkgs.log"
+rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
 
 NEEDS_DEVEL=${1-""}
 PKG_NAME_TAIL="headless"
@@ -20,26 +20,26 @@ echo "${ME}: Needs development packages? ${NEEDS_DEVEL}"
 echo " "
 echo "${ME}: Listing versions of java installed: "
 yum list installed | grep -i "\(java\|jre\)" | tee -a ${JAVA_INSTALLED_PKGS_LOGS}
-touch ${JAVA_17_INSTALLED_PKGS_LOGS}
-grep -i "java-17" ${JAVA_INSTALLED_PKGS_LOGS} > ${JAVA_17_INSTALLED_PKGS_LOGS} || echo "No java 17 packages found."
+touch ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
+grep -i "java-21" ${JAVA_INSTALLED_PKGS_LOGS} > ${JAVA_TARGET_INSTALLED_PKGS_LOGS} || echo "No java 21 packages found."
 
 NEEDS_INSTALLATION="true"
-if [ -f ${JAVA_17_INSTALLED_PKGS_LOGS} ]; then
-    if grep -qi "${PKG_NAME_TAIL}" ${JAVA_17_INSTALLED_PKGS_LOGS} ; then
+if [ -f ${JAVA_TARGET_INSTALLED_PKGS_LOGS} ]; then
+    if grep -qi "${PKG_NAME_TAIL}" ${JAVA_TARGET_INSTALLED_PKGS_LOGS} ; then
         NEEDS_INSTALLATION="false"
     fi
 fi
 
 # We need devel package in masters to have jar binary.
 if [ "true" == "${NEEDS_INSTALLATION}" ]; then
-    echo "${ME}:Java-17 is *not* installed. Installing..."
+    echo "${ME}:Java-21 is *not* installed. Installing..."
     if [ "true" == "${NEEDS_DEVEL}" ]; then
-        yum -y install java-17-openjdk-devel
+        yum -y install java-21-openjdk-devel
     else
-        yum -y install java-17-openjdk-headless
+        yum -y install java-21-openjdk-headless
     fi
 else
-    echo "${ME}: Java-17 is already installed."
+    echo "${ME}: Java-21 is already installed."
 fi
 
 if grep -qi "java-1.8" ${JAVA_INSTALLED_PKGS_LOGS} ; then
@@ -56,14 +56,21 @@ else
     echo "${ME}: Java-11 is not installed. Correct."
 fi
 
-if grep -qi "java-21" ${JAVA_INSTALLED_PKGS_LOGS} ; then
-    echo "${ME}: Java-21 is installed. Removing..."
-    yum -y remove java-21*
+if grep -qi "java-17" ${JAVA_INSTALLED_PKGS_LOGS} ; then
+    echo "${ME}: Java-17 is installed. Removing..."
+    yum -y remove java-17*
 else
-    echo "${ME}: Java-21 is not installed. Correct."
+    echo "${ME}: Java-17 is not installed. Correct."
 fi
 
-rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_17_INSTALLED_PKGS_LOGS}
+if grep -qi "java-25" ${JAVA_INSTALLED_PKGS_LOGS} ; then
+    echo "${ME}: Java-25 is installed. Removing..."
+    yum -y remove java-25*
+else
+    echo "${ME}: Java-25 is not installed. Correct."
+fi
+
+rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
 
 source /etc/profile.d/set-default-java.sh
 java -version
diff --git a/jenkins/agent-base/set-default-java.sh b/jenkins/agent-base/set-default-java.sh
index a01d520a1..5c27ec4d5 100644
--- a/jenkins/agent-base/set-default-java.sh
+++ b/jenkins/agent-base/set-default-java.sh
@@ -1,7 +1,8 @@
 #!/bin/bash
 set -eu -o pipefail
 
-JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-17-openjdk-.*\.x86_64" | awk '{print $NF}' | head -1)
+JAVA_VERSION="21"
+JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-${JAVA_VERSION}-openjdk-.*\.x86_64" | awk '{print $NF}' | head -1)
 export JAVA_HOME="/usr/lib/jvm/${JAVA_HOME_FOLDER}"
-export USE_JAVA_VERSION=java-17
+export USE_JAVA_VERSION=java-${JAVA_VERSION}
 alternatives --set java ${JAVA_HOME}/bin/java
diff --git a/jenkins/agent-base/use-j17.sh b/jenkins/agent-base/use-j21.sh
similarity index 61%
rename from jenkins/agent-base/use-j17.sh
rename to jenkins/agent-base/use-j21.sh
index 69c3805d8..dd8e506bd 100644
--- a/jenkins/agent-base/use-j17.sh
+++ b/jenkins/agent-base/use-j21.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
-JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-17-openjdk-.*\.x86_64" | awk '{print $NF}' | head -1)
-JAVA_VERSION="17"
+JAVA_VERSION="21"
+JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-${JAVA_VERSION}-openjdk-.*\.x86_64" | awk '{print $NF}' | head -1)
 
 function msg_and_exit() {
   echo "ERROR: ${1}"
@@ -36,3 +36,16 @@ else
   msg_and_exit "Cannot configure JAVA_HOME environment variable to ${JAVA_HOME}"
 fi
 echo "JAVA_HOME: $JAVA_HOME"
+
+# If not sourced, print the export command so parent shell can eval it
+if [ "${BASH_SOURCE[0]}" == "${0}" ]; then
+  echo ""
+  echo "================================================================================="
+  echo "WARNING: Script executed as subprocess - JAVA_HOME will NOT persist!"
+  echo "-----"
+  echo "Usage Options:"
+  echo "  Option 1 (source):   source ${BASH_SOURCE[0]}"
+  echo "  Option 2 (dot):      . ${BASH_SOURCE[0]}"
+  echo "================================================================================="
+  echo ""
+fi
diff --git a/jenkins/master/Dockerfile.ubi8 b/jenkins/master/Dockerfile.ubi8
index 47332ee83..11b71354c 100644
--- a/jenkins/master/Dockerfile.ubi8
+++ b/jenkins/master/Dockerfile.ubi8
@@ -1,6 +1,6 @@
 FROM quay.io/openshift/origin-jenkins
 
-ENV JAVA_HOME /usr/lib/jvm/jre-17
+ENV JAVA_HOME /usr/lib/jvm/jre-21
 
 # ODS defaults, available to use within pipelines.
 ARG ODS_NAMESPACE
diff --git a/jenkins/master/Dockerfile.ubi9 b/jenkins/master/Dockerfile.ubi9
index a8e9241b3..094cf6a00 100644
--- a/jenkins/master/Dockerfile.ubi9
+++ b/jenkins/master/Dockerfile.ubi9
@@ -1,6 +1,6 @@
 FROM quay.io/openshift/origin-jenkins
 
-ENV JAVA_HOME /usr/lib/jvm/jre-17
+ENV JAVA_HOME /usr/lib/jvm/jre-21
 
 # ODS defaults, available to use within pipelines.
 ARG ODS_NAMESPACE
diff --git a/jenkins/master/scripts_for_usr-local-bin/ensure_java_jre_is_adequate.sh b/jenkins/master/scripts_for_usr-local-bin/ensure_java_jre_is_adequate.sh
index 9c0b3c23e..689040ffc 100755
--- a/jenkins/master/scripts_for_usr-local-bin/ensure_java_jre_is_adequate.sh
+++ b/jenkins/master/scripts_for_usr-local-bin/ensure_java_jre_is_adequate.sh
@@ -3,8 +3,8 @@ set -eu -o pipefail
 
 ME="$(basename $0)"
 JAVA_INSTALLED_PKGS_LOGS="/tmp/java_installed_pkgs.log"
-JAVA_17_INSTALLED_PKGS_LOGS="/tmp/java_17_installed_pkgs.log"
-rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_17_INSTALLED_PKGS_LOGS}
+JAVA_TARGET_INSTALLED_PKGS_LOGS="/tmp/java_target_installed_pkgs.log"
+rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
 
 NEEDS_DEVEL=${1-""}
 PKG_NAME_TAIL="headless"
@@ -20,26 +20,26 @@ echo "${ME}: Needs development packages? ${NEEDS_DEVEL}"
 echo " "
 echo "${ME}: Listing versions of java installed: "
 yum list installed | grep -i "\(java\|jre\)" | tee -a ${JAVA_INSTALLED_PKGS_LOGS}
-touch ${JAVA_17_INSTALLED_PKGS_LOGS}
-grep -i "java-17" ${JAVA_INSTALLED_PKGS_LOGS} > ${JAVA_17_INSTALLED_PKGS_LOGS} || echo "No java 17 packages found."
+touch ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
+grep -i "java-21" ${JAVA_INSTALLED_PKGS_LOGS} > ${JAVA_TARGET_INSTALLED_PKGS_LOGS} || echo "No java 21 packages found."
 
 NEEDS_INSTALLATION="true"
-if [ -f ${JAVA_17_INSTALLED_PKGS_LOGS} ]; then
-    if grep -qi "${PKG_NAME_TAIL}" ${JAVA_17_INSTALLED_PKGS_LOGS} ; then
+if [ -f ${JAVA_TARGET_INSTALLED_PKGS_LOGS} ]; then
+    if grep -qi "${PKG_NAME_TAIL}" ${JAVA_TARGET_INSTALLED_PKGS_LOGS} ; then
         NEEDS_INSTALLATION="false"
     fi
 fi
 
 # We need devel package in masters to have jar binary.
 if [ "true" == "${NEEDS_INSTALLATION}" ]; then
-    echo "${ME}:Java-17 is *not* installed. Installing..."
+    echo "${ME}:Java-21 is *not* installed. Installing..."
     if [ "true" == "${NEEDS_DEVEL}" ]; then
-        yum -y install java-17-openjdk-devel
+        yum -y install java-21-openjdk-devel
     else
-        yum -y install java-17-openjdk-headless
+        yum -y install java-21-openjdk-headless
     fi
 else
-    echo "${ME}: Java-17 is already installed."
+    echo "${ME}: Java-21 is already installed."
 fi
 
 if grep -qi "java-1.8" ${JAVA_INSTALLED_PKGS_LOGS} ; then
@@ -56,19 +56,26 @@ else
     echo "${ME}: Java-11 is not installed. Correct."
 fi
 
-if grep -qi "java-21" ${JAVA_INSTALLED_PKGS_LOGS} ; then
-    echo "${ME}: Java-21 is installed. Removing..."
-    yum -y remove java-21*
+if grep -qi "java-17" ${JAVA_INSTALLED_PKGS_LOGS} ; then
+    echo "${ME}: Java-17 is installed. Removing..."
+    yum -y remove java-17*
 else
-    echo "${ME}: Java-21 is not installed. Correct."
+    echo "${ME}: Java-17 is not installed. Correct."
 fi
 
-rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_17_INSTALLED_PKGS_LOGS}
+if grep -qi "java-25" ${JAVA_INSTALLED_PKGS_LOGS} ; then
+    echo "${ME}: Java-25 is installed. Removing..."
+    yum -y remove java-25*
+else
+    echo "${ME}: Java-25 is not installed. Correct."
+fi
+
+rm -fv ${JAVA_INSTALLED_PKGS_LOGS} ${JAVA_TARGET_INSTALLED_PKGS_LOGS}
 
 NO_JAVA_LINK="false"
 java -version || NO_JAVA_LINK="true"
 if [ "true" == "${NO_JAVA_LINK}" ]; then
-    JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-17-openjdk-17.*\.x86_64" | awk '{print $NF}' | head -1)
+    JAVA_HOME_FOLDER=$(ls -lah /usr/lib/jvm | grep "java-21-openjdk-21.*\.x86_64" | awk '{print $NF}' | head -1)
     JAVA_HOME="/usr/lib/jvm/${JAVA_HOME_FOLDER}"
     alternatives --set java ${JAVA_HOME}/bin/java
 fi