Index: lucene/core/src/java/org/apache/lucene/util/Constants.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/util/Constants.java	(revision 1367529)
+++ lucene/core/src/java/org/apache/lucene/util/Constants.java	(working copy)
@@ -108,6 +108,10 @@
     } else {
       JRE_IS_MINIMUM_JAVA8 = false;
     }
+    
+    if ("21.0-b17".equals(JVM_VERSION) && "Oracle Corporation".equals(JVM_VENDOR)) {
+      throw new RuntimeException("This JVM is incompatible with Lucene, please upgrade to 1.7.0_01.");
+    }
   }
 
   // this method prevents inlining the final version constant in compiled classes,