--- a/src/hotspot/share/memory/heapInspection.cpp	Tue Mar 26 09:16:07 2019 +0100
+++ b/src/hotspot/share/memory/heapInspection.cpp	Tue Mar 26 10:23:11 2019 +0100
@@ -121,6 +121,11 @@
 }
 
 KlassInfoEntry* KlassInfoBucket::lookup(Klass* const k) {
+  // Can happen if k is an archived class that we haven't loaded yet.
+  if (k->java_mirror() == NULL) {
+    return NULL;
+  }
+
   KlassInfoEntry* elt = _list;
   while (elt != NULL) {
     if (elt->is_equal(k)) {
@@ -202,7 +207,8 @@
   assert(_buckets != NULL, "Allocation failure should have been caught");
   KlassInfoEntry*  e   = _buckets[idx].lookup(k);
   // Lookup may fail if this is a new klass for which we
-  // could not allocate space for an new entry.
+  // could not allocate space for an new entry, or if it's
+  // an archived class that we haven't loaded yet.
   assert(e == NULL || k == e->klass(), "must be equal");
   return e;
 }

--- a/src/hotspot/share/services/heapDumper.cpp	Tue Mar 26 09:16:07 2019 +0100
+++ b/src/hotspot/share/services/heapDumper.cpp	Tue Mar 26 10:23:11 2019 +0100
@@ -958,6 +958,11 @@
 // creates HPROF_GC_INSTANCE_DUMP record for the given object
 void DumperSupport::dump_instance(DumpWriter* writer, oop o) {
   Klass* k = o->klass();
+  if (k->java_mirror() == NULL) {
+    // Ignoring this object since the corresponding java mirror is not loaded.
+    // Might be a dormant archive object.
+    return;
+  }
 
   writer->write_u1(HPROF_GC_INSTANCE_DUMP);
   writer->write_objectID(o);