diff --git a/apm-agent-plugins/apm-slf4j-plugin/src/main/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListener.java b/apm-agent-plugins/apm-slf4j-plugin/src/main/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListener.java
index 6639ca6115..b51d8402ec 100644
--- a/apm-agent-plugins/apm-slf4j-plugin/src/main/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListener.java
+++ b/apm-agent-plugins/apm-slf4j-plugin/src/main/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListener.java
@@ -30,6 +30,8 @@
 import co.elastic.apm.agent.impl.transaction.TraceContext;
 import co.elastic.apm.agent.impl.transaction.TraceContextHolder;
 import co.elastic.apm.agent.logging.LoggingConfiguration;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
 import java.lang.invoke.MethodHandle;
@@ -44,6 +46,10 @@ public class Slf4JMdcActivationListener implements ActivationListener {
     private static final String TRACE_ID = "trace.id";
     private static final String SPAN_ID = "span.id";
     private static final String TRANSACTION_ID = "transaction.id";
+    private static final Logger logger = LoggerFactory.getLogger(Slf4JMdcActivationListener.class);
+
+    // Never invoked- only used for caching ClassLoaders that can't load the slf4j MDC class
+    private static final MethodHandle NOOP = MethodHandles.constant(String.class, "ClassLoader cannot load slf4j API");
 
     private final WeakKeySoftValueLoadingCache<ClassLoader, MethodHandle> mdcPutMethodHandleCache =
         new WeakKeySoftValueLoadingCache<>(new WeakKeySoftValueLoadingCache.ValueSupplier<ClassLoader, MethodHandle>() {
@@ -53,9 +59,9 @@ public MethodHandle get(ClassLoader classLoader) {
                 try {
                     return MethodHandles.lookup()
                         .findStatic(classLoader.loadClass(ORG_SLF4J_MDC), "put", MethodType.methodType(void.class, String.class, String.class));
-                } catch (Exception ignore) {
-                    // this class loader does not have the slf4j api
-                    return null;
+                } catch (Exception e) {
+                    logger.warn("Class loader " + classLoader + " cannot load slf4j API", e);
+                    return NOOP;
                 }
             }
         });
@@ -68,8 +74,8 @@ public MethodHandle get(ClassLoader classLoader) {
                     return MethodHandles.lookup()
                         .findStatic(classLoader.loadClass(ORG_SLF4J_MDC), "remove", MethodType.methodType(void.class, String.class));
                 } catch (Exception ignore) {
-                    // this class loader does not have the slf4j api
-                    return null;
+                    // No need to log - logged already when populated the put cache
+                    return NOOP;
                 }
             }
         });
@@ -84,10 +90,10 @@ public Slf4JMdcActivationListener(ElasticApmTracer tracer) {
     @Override
     public void beforeActivate(TraceContextHolder<?> context) throws Throwable {
         if (config.isLogCorrelationEnabled()) {
-            ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+            ClassLoader contextClassLoader = getContextClassLoader();
 
             MethodHandle put = mdcPutMethodHandleCache.get(contextClassLoader);
-            if (put != null) {
+            if (put != null && put != NOOP) {
                 TraceContext traceContext = context.getTraceContext();
                 put.invokeExact(SPAN_ID, traceContext.getId().toString());
                 if (tracer.getActive() == null) {
@@ -102,11 +108,11 @@ public void beforeActivate(TraceContextHolder<?> context) throws Throwable {
     public void afterDeactivate() throws Throwable {
         if (config.isLogCorrelationEnabled()) {
 
-            ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+            ClassLoader contextClassLoader = getContextClassLoader();
             TraceContextHolder active = tracer.getActive();
 
             MethodHandle remove = mdcRemoveMethodHandleCache.get(contextClassLoader);
-            if (remove != null) {
+            if (remove != null && remove != NOOP) {
                 if (active == null) {
                     remove.invokeExact(SPAN_ID);
                     remove.invokeExact(TRACE_ID);
@@ -116,10 +122,15 @@ public void afterDeactivate() throws Throwable {
 
             if (active != null) {
                 MethodHandle put = mdcPutMethodHandleCache.get(contextClassLoader);
-                if (put != null) {
+                if (put != null && put != NOOP) {
                     put.invokeExact(SPAN_ID, active.getTraceContext().getId().toString());
                 }
             }
         }
     }
+
+    private ClassLoader getContextClassLoader() {
+        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+        return (contextClassLoader != null) ? contextClassLoader : ClassLoader.getSystemClassLoader();
+    }
 }
diff --git a/apm-agent-plugins/apm-slf4j-plugin/src/test/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListenerTest.java b/apm-agent-plugins/apm-slf4j-plugin/src/test/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListenerTest.java
index 12acf43f7c..a2d2800198 100644
--- a/apm-agent-plugins/apm-slf4j-plugin/src/test/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListenerTest.java
+++ b/apm-agent-plugins/apm-slf4j-plugin/src/test/java/co/elastic/apm/agent/slf4j/Slf4JMdcActivationListenerTest.java
@@ -37,6 +37,8 @@
 import org.slf4j.MDC;
 
 import java.io.IOException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatCode;
@@ -79,14 +81,60 @@ void testMdcIntegrationTransactionScopeInDifferentThread() throws Exception {
         when(loggingConfiguration.isLogCorrelationEnabled()).thenReturn(true);
         Transaction transaction = tracer.startTransaction(TraceContext.asRoot(), null, null).withType("request").withName("test");
         assertMdcIsEmpty();
+        final CompletableFuture<Boolean> result = new CompletableFuture<>();
         Thread thread = new Thread(() -> {
             assertMdcIsEmpty();
             try (Scope scope = transaction.activateInScope()) {
                 assertMdcIsSet(transaction);
             }
             assertMdcIsEmpty();
+            result.complete(true);
         });
         thread.start();
+        assertThat(result.get(1000, TimeUnit.MILLISECONDS).booleanValue()).isTrue();
+        assertMdcIsEmpty();
+        thread.join();
+        transaction.end();
+    }
+
+    @Test
+    void testNoopWhenClassLoaderCantLoadMdc() throws Exception {
+        when(loggingConfiguration.isLogCorrelationEnabled()).thenReturn(true);
+        Transaction transaction = tracer.startTransaction(TraceContext.asRoot(), null, null).withType("request").withName("test");
+        assertMdcIsEmpty();
+        final CompletableFuture<Boolean> result = new CompletableFuture<>();
+        Thread thread = new Thread(() -> {
+            assertMdcIsEmpty();
+            try (Scope scope = transaction.activateInScope()) {
+                assertMdcIsEmpty();
+            }
+            result.complete(true);
+        });
+        thread.setContextClassLoader(ClassLoader.getPlatformClassLoader());
+        thread.start();
+        assertThat(result.get(1000, TimeUnit.MILLISECONDS).booleanValue()).isTrue();
+        assertMdcIsEmpty();
+        thread.join();
+        transaction.end();
+    }
+
+    @Test
+    void testWithNullContextClassLoader() throws Exception {
+        when(loggingConfiguration.isLogCorrelationEnabled()).thenReturn(true);
+        Transaction transaction = tracer.startTransaction(TraceContext.asRoot(), null, null).withType("request").withName("test");
+        assertMdcIsEmpty();
+        final CompletableFuture<Boolean> result = new CompletableFuture<>();
+        Thread thread = new Thread(() -> {
+            assertMdcIsEmpty();
+            try (Scope scope = transaction.activateInScope()) {
+                assertMdcIsSet(transaction);
+            }
+            assertMdcIsEmpty();
+            result.complete(true);
+        });
+        thread.setContextClassLoader(null);
+        thread.start();
+        assertThat(result.get(1000, TimeUnit.MILLISECONDS).booleanValue()).isTrue();
         assertMdcIsEmpty();
         thread.join();
         transaction.end();
@@ -102,15 +150,17 @@ void testMdcIntegrationContextScopeInDifferentThread() throws Exception {
             final Span child = transaction.createSpan();
             try (Scope childScope = child.activateInScope()) {
                 assertMdcIsSet(child);
+                final CompletableFuture<Boolean> result = new CompletableFuture<>();
                 Thread thread = new Thread(() -> {
                     assertMdcIsEmpty();
                     try (Scope otherThreadScope = child.getTraceContext().activateInScope()) {
                         assertMdcIsSet(child);
                     }
                     assertMdcIsEmpty();
+                    result.complete(true);
                 });
                 thread.start();
-                thread.join();
+                assertThat(result.get(1000, TimeUnit.MILLISECONDS).booleanValue()).isTrue();
                 assertMdcIsSet(child);
             }
             assertMdcIsSet(transaction);