diff -r 146468e05dd4 -r 8f45302a9ff0 src/Pure/Tools/build_process.scala
--- a/src/Pure/Tools/build_process.scala	Thu Aug 10 19:58:23 2023 +0200
+++ b/src/Pure/Tools/build_process.scala	Thu Aug 10 20:30:37 2023 +0200
@@ -995,8 +995,8 @@
     val cancelled = progress.stopped || !ancestor_results.forall(_.ok)
 
     if (!skipped && !cancelled) {
-      ML_Heap.restore(_database_server, session_name, store.output_heap(session_name),
-        cache = store.cache.compress)
+      val heaps = (session_name :: ancestor_results.map(_.name)).map(store.output_heap)
+      ML_Heap.restore(_database_server, heaps, cache = store.cache.compress)
     }
 
     val result_name = (session_name, worker_uuid, build_uuid)