diff --git a/.github/workflows/ci-prb-reports.yml b/.github/workflows/ci-prb-reports.yml
index 2fabe824d2..9d6627c22e 100644
--- a/.github/workflows/ci-prb-reports.yml
+++ b/.github/workflows/ci-prb-reports.yml
@@ -10,7 +10,7 @@ jobs:
     strategy:
       # Matrix should be coordinated with ci-prb.yml.
       matrix:
-        java: [ 8, 11, 17, 20 ]
+        java: [ 8, 11, 17, 21 ]
         os: [ ubuntu-latest ]
     steps:
       - name: Download Artifacts
diff --git a/.github/workflows/ci-prb.yml b/.github/workflows/ci-prb.yml
index 4e0dcaea38..4b6a28945f 100644
--- a/.github/workflows/ci-prb.yml
+++ b/.github/workflows/ci-prb.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        java: [ 8, 11, 17, 20 ]
+        java: [ 8, 11, 17, 21 ]
         os: [ ubuntu-latest ]
     steps:
       - name: Checkout Code
diff --git a/.github/workflows/ci-prq-reports.yml b/.github/workflows/ci-prq-reports.yml
index a7892ea028..ebc62762b4 100644
--- a/.github/workflows/ci-prq-reports.yml
+++ b/.github/workflows/ci-prq-reports.yml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11, 17, 20 ]
+        java: [ 8, 11, 17, 21 ]
     steps:
       - name: Download Artifacts
         uses: dawidd6/action-download-artifact@268677152d06ba59fcec7a7f0b5d961b6ccd7e1e
diff --git a/.github/workflows/ci-prq.yml b/.github/workflows/ci-prq.yml
index c0476daef2..a51a3841a3 100644
--- a/.github/workflows/ci-prq.yml
+++ b/.github/workflows/ci-prq.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11, 17, 20 ]
+        java: [ 8, 11, 17, 21 ]
     steps:
       - name: Checkout Code
         uses: actions/checkout@v4
diff --git a/build.gradle b/build.gradle
index 42f13ac947..7e7c79adf4 100644
--- a/build.gradle
+++ b/build.gradle
@@ -41,6 +41,10 @@ task validateLocalDocSite(type: Exec) {
 quality.dependsOn validateLocalDocSite
 
 subprojects {
+  // mockito 5 only supports jdk11+
+  if (JavaVersion.current() < JavaVersion.VERSION_11) {
+    project.setProperty("mockitoCoreVersion", mockitoCorePreJdk11Version)
+  }
   // Used by ci-release.yaml to determine which modules need to be built/released with JDK11.
   task printJavaTargetCompatibility {
     doLast {
diff --git a/gradle.properties b/gradle.properties
index f911224340..c1e0da6735 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -72,7 +72,9 @@ junit5Version=5.9.3
 testngVersion=7.5
 assertJCoreVersion=3.24.2
 hamcrestVersion=2.2
-mockitoCoreVersion=4.11.0
+mockitoCoreVersion=5.5.0
+# mockito version is overridden for <jdk11 due to incompatibilities with newer bytebuddy and class format
+mockitoCorePreJdk11Version=4.11.0
 spotbugsPluginVersion=5.0.13
 
 apacheDirectoryServerVersion=1.5.7
diff --git a/servicetalk-gradle-plugin-internal/src/main/groovy/io/servicetalk/gradle/plugin/internal/ServiceTalkLibraryPlugin.groovy b/servicetalk-gradle-plugin-internal/src/main/groovy/io/servicetalk/gradle/plugin/internal/ServiceTalkLibraryPlugin.groovy
index 3831b49e27..ddbb30a25b 100644
--- a/servicetalk-gradle-plugin-internal/src/main/groovy/io/servicetalk/gradle/plugin/internal/ServiceTalkLibraryPlugin.groovy
+++ b/servicetalk-gradle-plugin-internal/src/main/groovy/io/servicetalk/gradle/plugin/internal/ServiceTalkLibraryPlugin.groovy
@@ -280,6 +280,8 @@ final class ServiceTalkLibraryPlugin extends ServiceTalkCorePlugin {
           xml.enabled = project.ext.isCiBuild
           html.enabled = !project.ext.isCiBuild
         }
+        // https://github.com/spotbugs/spotbugs/issues/2567
+        enabled = JavaVersion.current() < JavaVersion.VERSION_21
       }
 
       tasks.withType(SpotBugsTask).all {