diff -r e0443773ef1a -r b5e6f0d137a7 src/Pure/Tools/build.scala
--- a/src/Pure/Tools/build.scala	Sat Nov 21 20:35:48 2020 +0100
+++ b/src/Pure/Tools/build.scala	Sat Nov 21 21:02:38 2020 +0100
@@ -502,11 +502,12 @@
         val presentation_dir = presentation.dir(store)
         progress.echo("Presentation in " + presentation_dir.absolute)
 
-        for ((_, (session_name, _)) <- presentation_chapters) {
-          progress.expose_interrupt()
-          progress.echo("Presenting " + session_name + " ...")
-          Presentation.session_html(session_name, deps, store, presentation)
-        }
+        using(store.open_database_context(deps.sessions_structure))(db_context =>
+          for ((_, (session_name, _)) <- presentation_chapters) {
+            progress.expose_interrupt()
+            progress.echo("Presenting " + session_name + " ...")
+            Presentation.session_html(session_name, deps, db_context, presentation)
+          })
 
         val browser_chapters =
           presentation_chapters.groupBy(_._1).