diff --git a/build.gradle b/build.gradle
index 1b9f272..4159002 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,10 +4,10 @@ plugins {
     id "pmd"
     id 'maven-publish'
     id 'signing'
-    id "io.github.gradle-nexus.publish-plugin" version "1.3.0"
-    id "com.github.spotbugs" version "5.0.14"
-    id "org.cyclonedx.bom" version "1.7.2"
-    id "org.xbib.gradle.plugin.asciidoctor" version "2.5.2.2"
+    id "io.github.gradle-nexus.publish-plugin" version "2.0.0-rc-1"
+    //id "com.github.spotbugs" version "6.0.0-beta.3"
+    id "org.cyclonedx.bom" version "1.7.4"
+    id "org.xbib.gradle.plugin.asciidoctor" version "3.0.0"
 }
 
 wrapper {
@@ -31,14 +31,14 @@ ext {
 }
 
 subprojects {
-    apply from: rootProject.file('gradle/ide/idea.gradle')
+    //apply from: rootProject.file('gradle/ide/idea.gradle')
     apply from: rootProject.file('gradle/repositories/maven.gradle')
     apply from: rootProject.file('gradle/compile/java.gradle')
     apply from: rootProject.file('gradle/test/junit5.gradle')
     apply from: rootProject.file('gradle/documentation/asciidoc.gradle')
     apply from: rootProject.file('gradle/quality/checkstyle.gradle')
     apply from: rootProject.file('gradle/quality/pmd.gradle')
-    apply from: rootProject.file('gradle/quality/spotbugs.gradle')
+    //apply from: rootProject.file('gradle/quality/spotbugs.gradle')
     apply from: rootProject.file('gradle/publish/maven.gradle')
 }
 apply from: rootProject.file('gradle/publish/sonatype.gradle')
diff --git a/gradle.properties b/gradle.properties
index 4bc172e..4f4f703 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 group = org.xbib
 name = z3950
-version = 5.1.8
+version = 6.0.0
 
 org.gradle.warning.mode = ALL
diff --git a/gradle/compile/java.gradle b/gradle/compile/java.gradle
index 5f46bfb..0af4be7 100644
--- a/gradle/compile/java.gradle
+++ b/gradle/compile/java.gradle
@@ -2,17 +2,12 @@
 apply plugin: 'java-library'
 
 java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(21)
+    }
     modularity.inferModulePath.set(true)
-}
-
-compileJava {
-    sourceCompatibility = JavaVersion.VERSION_17
-    targetCompatibility = JavaVersion.VERSION_17
-}
-
-compileTestJava {
-    sourceCompatibility = JavaVersion.VERSION_17
-    targetCompatibility = JavaVersion.VERSION_17
+    withSourcesJar()
+    withJavadocJar()
 }
 
 jar {
@@ -21,21 +16,9 @@ jar {
     }
 }
 
-task sourcesJar(type: Jar, dependsOn: classes) {
-    classifier 'sources'
-    from sourceSets.main.allSource
-    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
-}
-
-task javadocJar(type: Jar, dependsOn: javadoc) {
-    classifier 'javadoc'
-}
-
-artifacts {
-    archives sourcesJar, javadocJar
-}
-
 tasks.withType(JavaCompile) {
+    options.fork = true
+    options.forkOptions.jvmArgs += ['-Duser.language=en','-Duser.country=US']
     options.compilerArgs.add('-Xlint:all,-exports')
     options.encoding = 'UTF-8'
 }
diff --git a/gradle/test/junit5.gradle b/gradle/test/junit5.gradle
index f111a98..57f9e67 100644
--- a/gradle/test/junit5.gradle
+++ b/gradle/test/junit5.gradle
@@ -1,8 +1,10 @@
 dependencies {
-    testImplementation libs.junit.jupiter.api
-    testImplementation libs.junit.jupiter.params
-    testImplementation libs.hamcrest
-    testRuntimeOnly libs.junit.jupiter.engine
+    testImplementation testLibs.junit.jupiter.api
+    testImplementation testLibs.junit.jupiter.params
+    testImplementation testLibs.hamcrest
+    testRuntimeOnly testLibs.junit.jupiter.engine
+    testRuntimeOnly testLibs.junit.jupiter.vintage
+    testRuntimeOnly testLibs.junit.jupiter.platform.launcher
 }
 
 test {
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 249e583..7f93135 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 8fad3f5..8838ba9 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index a69d9cb..1aa94a4 100755
--- a/gradlew
+++ b/gradlew
@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +80,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,22 +131,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,11 +198,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
diff --git a/gradlew.bat b/gradlew.bat
index 53a6b23..6689b85 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -26,6 +26,7 @@ if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
 if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
diff --git a/settings.gradle b/settings.gradle
index 3c1637d..701923c 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,16 +1,24 @@
+pluginManagement {
+    repositories {
+        mavenLocal()
+        mavenCentral {
+            metadataSources {
+                mavenPom()
+                artifact()
+                ignoreGradleMetadataRedirection()
+            }
+        }
+        gradlePluginPortal()
+    }
+}
+
+
 dependencyResolutionManagement {
     versionCatalogs {
         libs {
-            version('gradle', '7.5.1')
-            version('groovy', '4.0.11')
-            version('junit', '5.9.2')
-            version('junit4', '4.13.2')
-            version('netty', '4.1.90.Final')
-            library('junit-jupiter-api', 'org.junit.jupiter', 'junit-jupiter-api').versionRef('junit')
-            library('junit-jupiter-params', 'org.junit.jupiter', 'junit-jupiter-params').versionRef('junit')
-            library('junit-jupiter-engine', 'org.junit.jupiter', 'junit-jupiter-engine').versionRef('junit')
-            library('junit-jupiter-vintage', 'org.junit.vintage', 'junit-vintage-engine').versionRef('junit4')
-            library('hamcrest', 'org.hamcrest', 'hamcrest-library').version('2.2')
+            version('gradle', '8.4')
+            version('groovy', '4.0.15')
+            version('netty', '4.1.100.Final')
             library('cql-common', 'org.xbib', 'cql-common').version('5.0.0')
             library('netty-transport', 'io.netty', 'netty-transport').versionRef('netty')
             library('netty-handler', 'io.netty', 'netty-handler').versionRef('netty')
@@ -27,6 +35,16 @@ dependencyResolutionManagement {
             library('groovy-test', 'org.apache.groovy', 'groovy-test').versionRef('groovy')
             library('marc', 'org.xbib', 'marc').version('2.9.21')
         }
+        testLibs {
+            version('junit', '5.10.0')
+            version('junit4', '4.13.2')
+            library('junit-jupiter-api', 'org.junit.jupiter', 'junit-jupiter-api').versionRef('junit')
+            library('junit-jupiter-params', 'org.junit.jupiter', 'junit-jupiter-params').versionRef('junit')
+            library('junit-jupiter-engine', 'org.junit.jupiter', 'junit-jupiter-engine').versionRef('junit')
+            library('junit-jupiter-vintage', 'org.junit.vintage', 'junit-vintage-engine').versionRef('junit')
+            library('junit-jupiter-platform-launcher', 'org.junit.platform', 'junit-platform-launcher').version('1.10.0')
+            library('hamcrest', 'org.hamcrest', 'hamcrest-library').version('2.2')
+        }
     }
 }
 
diff --git a/z3950-common/build.gradle b/z3950-common/build.gradle
index 7e8051e..45df091 100644
--- a/z3950-common/build.gradle
+++ b/z3950-common/build.gradle
@@ -1,6 +1,6 @@
 plugins {
-    id 'org.xbib.gradle.plugin.jflex' version '1.4.0'
-    id 'org.xbib.gradle.plugin.jacc' version '1.4.0'
+    id 'org.xbib.gradle.plugin.jflex' version '3.0.2'
+    id 'org.xbib.gradle.plugin.jacc' version '3.0.2'
 }
 
 dependencies {
@@ -11,7 +11,7 @@ dependencies {
 sourceSets {
     main {
         java {
-            srcDirs 'build/generated-src'
+            srcDirs "build/generated-src"
         }
     }
-}
\ No newline at end of file
+}
diff --git a/z3950-groovy/build.gradle b/z3950-groovy/build.gradle
index caa33c7..6c443f9 100644
--- a/z3950-groovy/build.gradle
+++ b/z3950-groovy/build.gradle
@@ -3,7 +3,6 @@ apply from: rootProject.file('gradle/compile/groovy.gradle')
 dependencies {
     api project(':z3950-client-jdk')
     api libs.groovy.xml
-    testRuntimeOnly libs.junit.jupiter.vintage
     testImplementation libs.groovy
     testImplementation libs.groovy.json
     testImplementation libs.groovy.nio