diff -r e43ef311d595 -r 1008b8e7c78d src/Pure/Admin/build_history.scala
--- a/src/Pure/Admin/build_history.scala	Sat Jun 14 14:37:34 2025 +0200
+++ b/src/Pure/Admin/build_history.scala	Sat Jun 14 17:10:18 2025 +0200
@@ -204,9 +204,7 @@
       File.write(other_isabelle.etc_preferences,
         cat_lines("build_log_verbose = true" :: more_preferences))
 
-      val isabelle_output =
-        other_isabelle.expand_path(
-          Path.explode("$ISABELLE_HOME_USER/heaps/$ML_IDENTIFIER"))
+      val isabelle_output = other_isabelle.user_output_dir
       val isabelle_output_log = isabelle_output + Path.explode("log")
       val isabelle_base_log = isabelle_output + Path.explode("../base_log")