diff --git a/platform/platform-api/src/com/intellij/ide/plugins/PluginManager.java b/platform/platform-api/src/com/intellij/ide/plugins/PluginManager.java
index 2fc1343026e7..7a191c6bd153 100644
--- a/platform/platform-api/src/com/intellij/ide/plugins/PluginManager.java
+++ b/platform/platform-api/src/com/intellij/ide/plugins/PluginManager.java
@@ -217,7 +217,7 @@ public class PluginManager {
     }
 
     final IdeaPluginDescriptor corePluginDescriptor = idToDescriptorMap.get(PluginId.getId(CORE_PLUGIN_ID));
-    assert corePluginDescriptor != null : CORE_PLUGIN_ID + " not found";
+    assert corePluginDescriptor != null : CORE_PLUGIN_ID + " not found; platform prefix is " + System.getProperty("idea.platform.prefix");
     for (IdeaPluginDescriptorImpl descriptor : result) {
       if (descriptor != corePluginDescriptor) {
         descriptor.insertDependency(corePluginDescriptor);