diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 96f01d483b..0f9c332eda 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -142,6 +142,7 @@ class Cache:
 
     def __init__(self, backend, library_database_instance=None):
         self.shutting_down = False
+        self.is_doing_rebuild_or_vacuum = False
         self.backend = backend
         self.library_database_instance = (None if library_database_instance is None else
                                           weakref.ref(library_database_instance))
@@ -2429,7 +2430,11 @@ class Cache:
 
     @write_api
     def vacuum(self):
-        self.backend.vacuum()
+        self.is_doing_rebuild_or_vacuum = True
+        try:
+            self.backend.vacuum()
+        finally:
+            self.is_doing_rebuild_or_vacuum = False
 
     def __del__(self):
         self.close()
diff --git a/src/calibre/gui2/actions/choose_library.py b/src/calibre/gui2/actions/choose_library.py
index 2b8396390e..b6cf8903a5 100644
--- a/src/calibre/gui2/actions/choose_library.py
+++ b/src/calibre/gui2/actions/choose_library.py
@@ -659,7 +659,9 @@ class ChooseLibraryAction(InterfaceAction):
         d = DBCheck(self.gui, db)
         try:
             d.start()
-            d.exec()
+            from calibre.gui2.widgets import BusyCursor
+            with BusyCursor():
+                d.exec()
             try:
                 m.close()
             except Exception:
diff --git a/src/calibre/gui2/dialogs/scheduler.py b/src/calibre/gui2/dialogs/scheduler.py
index 7a06c1d49f..c133d872ae 100644
--- a/src/calibre/gui2/dialogs/scheduler.py
+++ b/src/calibre/gui2/dialogs/scheduler.py
@@ -612,7 +612,9 @@ class Scheduler(QObject):
         from calibre.gui2.ui import get_gui
         gui = get_gui()
         if gui is not None:
-            return gui.current_db
+            ans = gui.current_db
+            if not ans.new_api.is_doing_rebuild_or_vacuum:
+                return ans
 
     def oldest_check(self):
         if self.oldest > 0:
diff --git a/src/calibre/gui2/library/models.py b/src/calibre/gui2/library/models.py
index 75d764ec4a..dacfcd98b5 100644
--- a/src/calibre/gui2/library/models.py
+++ b/src/calibre/gui2/library/models.py
@@ -966,6 +966,8 @@ class BooksModel(QAbstractTableModel):  # {{{
         self.column_to_dc_decorator_map = [self.dc_decorator.get(col, None) for col in self.column_map]
 
     def data(self, index, role):
+        if self.db.new_api.is_doing_rebuild_or_vacuum:
+            return None
         col = index.column()
         # in obscure cases where custom columns are both edited and added, for a time
         # the column map does not accurately represent the screen. In these cases,