diff --git a/maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java b/maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java
index 6c089863cc61..646a7515b60f 100644
--- a/maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java
+++ b/maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java
@@ -59,6 +59,8 @@
 import org.apache.maven.project.MavenProject;
 import org.codehaus.plexus.util.StringUtils;
 import org.eclipse.aether.SessionData;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * <p>
@@ -75,10 +77,14 @@
 @Singleton
 public class MojoExecutor
 {
+    private static final Logger LOGGER = LoggerFactory.getLogger( MojoExecutor.class );
 
     private final BuildPluginManager pluginManager;
+
     private final MavenPluginManager mavenPluginManager;
+
     private final LifecycleDependencyResolver lifeCycleDependencyResolver;
+
     private final ExecutionEventCatapult eventCatapult;
 
     private final ReadWriteLock aggregatorLock = new ReentrantReadWriteLock();
@@ -225,6 +231,16 @@ private void execute( MavenSession session, MojoExecution mojoExecution, Project
 
         try ( ProjectLock lock = new ProjectLock( session, mojoDescriptor, aggregatorLock ) )
         {
+            if ( session.isParallel() && mojoDescriptor.isAggregator() )
+            {
+                LOGGER.warn( "===" );
+                LOGGER.warn( "Executing aggregator Mojo in parallel build:" );
+                LOGGER.warn( "Aggregator Mojo requires exclusive access to reactor, " );
+                LOGGER.warn( "to prevent race conditions, an aggregating execution will block" );
+                LOGGER.warn( "all other executions until finished." );
+                LOGGER.warn( "===" );
+            }
+
             doExecute( session, mojoExecution, projectIndex, dependencyContext );
         }
     }