diff --git a/jcl-over-slf4j-blackbox/pom.xml b/jcl-over-slf4j-blackbox/pom.xml
index 953afe58..b6fde091 100644
--- a/jcl-over-slf4j-blackbox/pom.xml
+++ b/jcl-over-slf4j-blackbox/pom.xml
@@ -26,7 +26,6 @@
   </licenses>
 
   <properties>
-    <jdk.version>${jdk9.version}</jdk.version>
   </properties>
 
   <dependencies>
diff --git a/jcl-over-slf4j/src/main/java9/module-info.java b/jcl-over-slf4j/src/main/java/module-info.java
similarity index 100%
rename from jcl-over-slf4j/src/main/java9/module-info.java
rename to jcl-over-slf4j/src/main/java/module-info.java
diff --git a/jul-to-slf4j-blackbox/pom.xml b/jul-to-slf4j-blackbox/pom.xml
index 84ec6dfb..069ef23e 100644
--- a/jul-to-slf4j-blackbox/pom.xml
+++ b/jul-to-slf4j-blackbox/pom.xml
@@ -26,7 +26,6 @@
   </licenses>
 
   <properties>
-    <jdk.version>${jdk9.version}</jdk.version>
   </properties>
 
   <dependencies>
diff --git a/log4j-over-slf4j-blackbox/pom.xml b/log4j-over-slf4j-blackbox/pom.xml
index ebe95704..d8c981bc 100644
--- a/log4j-over-slf4j-blackbox/pom.xml
+++ b/log4j-over-slf4j-blackbox/pom.xml
@@ -26,7 +26,6 @@
   </licenses>
 
   <properties>
-    <jdk.version>${jdk9.version}</jdk.version>
   </properties>
 
   <dependencies>
diff --git a/log4j-over-slf4j/src/main/java9/module-info.java b/log4j-over-slf4j/src/main/java/module-info.java
similarity index 100%
rename from log4j-over-slf4j/src/main/java9/module-info.java
rename to log4j-over-slf4j/src/main/java/module-info.java
diff --git a/parent/pom.xml b/parent/pom.xml
index 8a2a9f92..8cbad002 100644
--- a/parent/pom.xml
+++ b/parent/pom.xml
@@ -29,9 +29,7 @@
     <project.build.outputTimestamp>2024-01-02T19:42:00Z</project.build.outputTimestamp>
     <latest.1.version>1.7.36</latest.1.version>
     <!-- java.util.ServiceLoader requires Java 6 -->
-    <jdk.version>8</jdk.version>
-    <!-- used in test modules, unpublished modules or where it does not matter -->
-    <jdk9.version>9</jdk9.version>
+    <jdk.version>11</jdk.version>
     <maven.compiler.source>${jdk.version}</maven.compiler.source>
     <maven.compiler.target>${jdk.version}</maven.compiler.target>
 
@@ -148,31 +146,6 @@
               <release>${jdk.version}</release>
             </configuration>
           </execution>
-
-          <execution>
-            <id>default-testCompile</id>
-            <goals>
-              <goal>testCompile</goal>
-            </goals>
-            <configuration>
-              <release>${jdk.version}</release>
-            </configuration>
-          </execution>
-
-          <execution>
-            <id>module-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <release>9</release>
-              <compileSourceRoots>
-                <compileSourceRoot>${project.basedir}/src/main/java9</compileSourceRoot>
-              </compileSourceRoots>
-              <multiReleaseOutput>true</multiReleaseOutput>
-            </configuration>
-          </execution>
         </executions>
 
       </plugin>
diff --git a/slf4j-api/pom.xml b/slf4j-api/pom.xml
index 131728a1..2d2b0f82 100755
--- a/slf4j-api/pom.xml
+++ b/slf4j-api/pom.xml
@@ -75,28 +75,6 @@
         </configuration>
       </plugin>
 
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>${maven-compiler-plugin.version}</version>
-        <executions>
-
-          <execution>
-            <id>module-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <release>${jdk9.version}</release>
-              <compileSourceRoots>
-                <compileSourceRoot>${project.basedir}/src/main/java9</compileSourceRoot>
-              </compileSourceRoots>
-              <multiReleaseOutput>true</multiReleaseOutput>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
     </plugins>
   </build>
 
diff --git a/slf4j-api/src/main/java9/module-info.java b/slf4j-api/src/main/java/module-info.java
similarity index 100%
rename from slf4j-api/src/main/java9/module-info.java
rename to slf4j-api/src/main/java/module-info.java
diff --git a/slf4j-jdk-platform-logging/pom.xml b/slf4j-jdk-platform-logging/pom.xml
index ac81709d..8b5c389b 100644
--- a/slf4j-jdk-platform-logging/pom.xml
+++ b/slf4j-jdk-platform-logging/pom.xml
@@ -20,7 +20,6 @@
   <url>https://www.slf4j.org</url>
 
   <properties>
-    <jdk.version>${jdk9.version}</jdk.version>
   </properties>
 
   <dependencies>
@@ -39,37 +38,6 @@
 
   <build>
     <plugins>
-      <!-- target Java 9+ -->
-<!--      <plugin>-->
-<!--        <groupId>org.apache.maven.plugins</groupId>-->
-<!--        <artifactId>maven-compiler-plugin</artifactId>-->
-<!--        <version>${maven-compiler-plugin.version}</version>-->
-<!--        <executions>-->
-<!--          <execution>-->
-<!--            <id>default-compile</id>-->
-<!--            <goals>-->
-<!--              <goal>compile</goal>-->
-<!--            </goals>-->
-<!--            <configuration>-->
-<!--              <source>9</source>-->
-<!--              <target>9</target>-->
-<!--              <release>9</release>-->
-<!--            </configuration>            -->
-<!--          </execution>-->
-<!--          <execution>-->
-<!--            <id>default-testCompile</id>-->
-<!--            <goals>-->
-<!--              <goal>testCompile</goal> -->
-<!--            </goals>-->
-<!--            <configuration>-->
-<!--              <source>9</source>-->
-<!--              <target>9</target>-->
-<!--              <release>9</release>-->
-<!--            </configuration>            -->
-<!--          </execution> -->
-<!--        </executions>        -->
-<!--      </plugin>-->
-
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
diff --git a/slf4j-jdk14/pom.xml b/slf4j-jdk14/pom.xml
index 60ec9360..555369ea 100755
--- a/slf4j-jdk14/pom.xml
+++ b/slf4j-jdk14/pom.xml
@@ -40,31 +40,7 @@
 
   <build>
     <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>${maven-compiler-plugin.version}</version>
-        <executions>
-
-          <execution>
-            <id>module-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <release>${jdk9.version}</release>
-              <compileSourceRoots>
-                <compileSourceRoot>${project.basedir}/src/main/java9</compileSourceRoot>
-              </compileSourceRoots>
-              <multiReleaseOutput>true</multiReleaseOutput>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
     </plugins>
-
-
   </build>
 
 </project>
diff --git a/slf4j-jdk14/src/main/java9/module-info.java b/slf4j-jdk14/src/main/java/module-info.java
similarity index 100%
rename from slf4j-jdk14/src/main/java9/module-info.java
rename to slf4j-jdk14/src/main/java/module-info.java
diff --git a/slf4j-migrator/src/main/java9/module-info.java b/slf4j-migrator/src/main/java/module-info.java
similarity index 100%
rename from slf4j-migrator/src/main/java9/module-info.java
rename to slf4j-migrator/src/main/java/module-info.java
diff --git a/slf4j-nop/pom.xml b/slf4j-nop/pom.xml
index 3718ec46..7efa36cb 100755
--- a/slf4j-nop/pom.xml
+++ b/slf4j-nop/pom.xml
@@ -40,28 +40,6 @@
 
   <build>
     <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>${maven-compiler-plugin.version}</version>
-        <executions>
-
-          <execution>
-            <id>module-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <release>${jdk9.version}</release>
-              <compileSourceRoots>
-                <compileSourceRoot>${project.basedir}/src/main/java9</compileSourceRoot>
-              </compileSourceRoots>
-              <multiReleaseOutput>true</multiReleaseOutput>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
     </plugins>
   </build>
 </project>
diff --git a/slf4j-nop/src/main/java9/module-info.java b/slf4j-nop/src/main/java/module-info.java
similarity index 100%
rename from slf4j-nop/src/main/java9/module-info.java
rename to slf4j-nop/src/main/java/module-info.java
diff --git a/slf4j-nop/src/test/java/org/slf4j/nop/MultithreadedInitializationTest.java b/slf4j-nop/src/test/java/org/slf4j/nop/MultithreadedInitializationTest.java
index 25cecb15..13062aab 100755
--- a/slf4j-nop/src/test/java/org/slf4j/nop/MultithreadedInitializationTest.java
+++ b/slf4j-nop/src/test/java/org/slf4j/nop/MultithreadedInitializationTest.java
@@ -31,6 +31,8 @@ import org.slf4j.LoggerFactory;
 import org.slf4j.LoggerFactoryFriend;
 
 import java.io.PrintStream;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Random;
 import java.util.concurrent.BrokenBarrierException;
 import java.util.concurrent.CyclicBarrier;
diff --git a/slf4j-reload4j/pom.xml b/slf4j-reload4j/pom.xml
index 4a1cbc9c..8abcc9f7 100644
--- a/slf4j-reload4j/pom.xml
+++ b/slf4j-reload4j/pom.xml
@@ -52,18 +52,53 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
         <configuration>
-          <forkCount>1</forkCount>
-          <reuseForks>false</reuseForks>
-          <reportFormat>plain</reportFormat>
-          <trimStackTrace>false</trimStackTrace>
-          <excludes>
-            <exclude>**/AllTest.java</exclude>
-            <exclude>**/PackageTest.java</exclude>
-          </excludes>
-          <!--<argLine>-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8001</argLine> -->
-          <!--<argLine>XXadd-opens log4j/org.apache.log4j=org.slf4j.log4j12</argLine>-->
+          <!--
+          java.lang.IllegalAccessException: class org.apache.log4j.helpers.OptionConverter
+          (in module ch.qos.reload4j) cannot access class org.slf4j.reload4j.testHarness.RecursiveAppender
+          (in module org.slf4j.reload4j) because module org.slf4j.reload4j does not export org.slf4j.reload4j.testHarness
+           to module ch.qos.reload4j
+
+          -->
+          <argLine>
+            --add-opens org.slf4j.reload4j/org.slf4j.reload4j.testHarness=ch.qos.reload4j
+          </argLine>
         </configuration>
       </plugin>
+      <!--        <executions>-->
+      <!--          <execution>-->
+      <!--            <id>default-test</id>-->
+      <!--            <configuration>-->
+      <!--              <parallel>classes</parallel>-->
+      <!--              <threadCount>8</threadCount>-->
+      <!--              <forkCount>1C</forkCount>-->
+      <!--              <reuseForks>true</reuseForks>-->
+      <!--              <reportFormat>plain</reportFormat>-->
+      <!--              <trimStackTrace>false</trimStackTrace>-->
+      <!--              <excludes>-->
+      <!--                <exclude>**/AllTest.java</exclude>-->
+      <!--                <exclude>**/PackageTest.java</exclude>-->
+      <!--                <exclude>org.slf4j.reload4j.EventFieldsTest</exclude>-->
+      <!--                <exclude>org.slf4j.testing.MultithreadedInitializationTest</exclude>-->
+      <!--              </excludes>-->
+      <!--            </configuration>-->
+      <!--          </execution>-->
+
+      <!--          <execution>-->
+      <!--            <id>singleJVM</id>-->
+      <!--            <goals>-->
+      <!--              <goal>test</goal>-->
+      <!--            </goals>-->
+      <!--            <configuration>-->
+      <!--              <forkCount>4</forkCount>-->
+      <!--              <reuseForks>false</reuseForks>-->
+      <!--              <includes>-->
+      <!--                <include>org.slf4j.testing.MultithreadedInitializationTest</include>-->
+      <!--                <include>org.slf4j.reload4j.EventFieldsTest</include>-->
+      <!--              </includes>-->
+      <!--            </configuration>-->
+      <!--          </execution>-->
+      <!--        </executions>-->
+      <!--      </plugin>-->
 
     </plugins>
   </build>
diff --git a/slf4j-reload4j/src/main/java9/module-info.java b/slf4j-reload4j/src/main/java/module-info.java
similarity index 100%
rename from slf4j-reload4j/src/main/java9/module-info.java
rename to slf4j-reload4j/src/main/java/module-info.java
diff --git a/slf4j-simple/pom.xml b/slf4j-simple/pom.xml
index 2e182389..7d8ce2c1 100755
--- a/slf4j-simple/pom.xml
+++ b/slf4j-simple/pom.xml
@@ -41,28 +41,6 @@
 
   <build>
     <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>${maven-compiler-plugin.version}</version>
-        <executions>
-
-          <execution>
-            <id>module-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <release>${jdk9.version}</release>
-              <compileSourceRoots>
-                <compileSourceRoot>${project.basedir}/src/main/java9</compileSourceRoot>
-              </compileSourceRoots>
-              <multiReleaseOutput>true</multiReleaseOutput>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
     </plugins>
 
   </build>
diff --git a/slf4j-simple/src/main/java9/module-info.java b/slf4j-simple/src/main/java/module-info.java
similarity index 100%
rename from slf4j-simple/src/main/java9/module-info.java
rename to slf4j-simple/src/main/java/module-info.java
diff --git a/slf4j-testing/pom.xml b/slf4j-testing/pom.xml
index 80d89134..338b2f8b 100644
--- a/slf4j-testing/pom.xml
+++ b/slf4j-testing/pom.xml
@@ -18,9 +18,7 @@
   <url>http://www.slf4j.org</url>
 
   <properties>
-    <jdk.version>${jdk9.version}</jdk.version>
     <module-name>org.slf4j.testing</module-name>
-    <maven.compiler.release>${jdk9.version}</maven.compiler.release>
   </properties>
 
   <dependencies>
@@ -46,24 +44,6 @@
           <skip>true</skip>
         </configuration>
       </plugin>
-
-<!--      <plugin>-->
-<!--        <groupId>org.apache.maven.plugins</groupId>-->
-<!--        <artifactId>maven-compiler-plugin</artifactId>-->
-<!--        <version>${maven-compiler-plugin.version}</version>-->
-
-<!--        <executions>-->
-<!--          <execution>-->
-<!--            <id>default-compile</id>-->
-<!--            <goals>-->
-<!--              <goal>compile</goal>-->
-<!--            </goals>-->
-<!--            <configuration combine.self="override">-->
-<!--              <release>${jdk9.version}</release>-->
-<!--            </configuration>-->
-<!--          </execution>-->
-<!--        </executions>-->
-<!--      </plugin>-->
     </plugins>
   </build>
 </project>
diff --git a/slf4j-testing/src/main/java/org/slf4j/testing/MultithreadedInitializationTest.java b/slf4j-testing/src/main/java/org/slf4j/testing/MultithreadedInitializationTest.java
index 0cb1ea25..4caedc6d 100644
--- a/slf4j-testing/src/main/java/org/slf4j/testing/MultithreadedInitializationTest.java
+++ b/slf4j-testing/src/main/java/org/slf4j/testing/MultithreadedInitializationTest.java
@@ -1,7 +1,10 @@
 package org.slf4j.testing;
 
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.event.EventRecordingLogger;
+import org.slf4j.helpers.SubstituteLogger;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -10,14 +13,10 @@ import java.util.concurrent.BrokenBarrierException;
 import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.atomic.AtomicLong;
 
-import org.junit.Test;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.slf4j.event.EventRecordingLogger;
-import org.slf4j.helpers.SubstituteLogger;
+import static org.junit.Assert.fail;
 
 abstract public class MultithreadedInitializationTest {
-    final protected static int THREAD_COUNT = 4 + Runtime.getRuntime().availableProcessors() * 2;
+    final protected static int THREAD_COUNT = 1;//4 + Runtime.getRuntime().availableProcessors() * 2;
 
     private final List<Logger> createdLoggers = Collections.synchronizedList(new ArrayList<>());