mfussenegger
diff --git a/‎com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/handler/AttachRequestHandler.java‎
Lines changed: 15 additions & 0 deletions b/‎com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/handler/AttachRequestHandler.java‎
Lines changed: 15 additions & 0 deletions
@@ -29,6 +29,7 @@
 import com.microsoft.java.debug.core.adapter.IDebugRequestHandler;
 import com.microsoft.java.debug.core.adapter.ISourceLookUpProvider;
 import com.microsoft.java.debug.core.adapter.IVirtualMachineManagerProvider;
+import com.microsoft.java.debug.core.protocol.Events;
 import com.microsoft.java.debug.core.protocol.Messages.Response;
 import com.microsoft.java.debug.core.protocol.Requests.Arguments;
 import com.microsoft.java.debug.core.protocol.Requests.AttachArguments;
@@ -58,6 +59,20 @@ public void handle(Command command, Arguments arguments, Response response, IDeb
                     attachArguments.timeout);
             context.setDebugSession(debugSession);
             logger.info("Attaching to debuggee VM succeeded.");
+
+            // If the debugger and debuggee run at the different JVM platforms, show a warning message.
+            if (debugSession != null) {
+                String debuggeeVersion = debugSession.getVM().version();
+                String debuggerVersion = System.getProperty("java.version");
+                if (!debuggerVersion.equals(debuggeeVersion)) {
+                    String warnMessage = String.format("[Warn] The debugger and the debuggee are running in different versions of JVMs. "
+                        + "You could see wrong source mapping results.\n"
+                        + "Debugger JVM version: %s\n"
+                        + "Debuggee JVM version: %s", debuggerVersion, debuggeeVersion);
+                    logger.warning(warnMessage);
+                    context.sendEvent(Events.OutputEvent.createConsoleOutput(warnMessage));
+                }
+            }
         } catch (IOException | IllegalConnectorArgumentsException e) {
             AdapterUtils.setErrorResponse(response, ErrorCode.ATTACH_FAILURE,
                     String.format("Failed to attach to remote debuggee VM. Reason: %s", e.toString()));