diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index aeca547119..0e54a4a0e8 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -1351,6 +1351,7 @@ class DB:
         self.close(force=force, unload_formatter_functions=False)
         self._conn = None
         self.conn
+        self.notes.reopen(self)
 
     def dump_and_restore(self, callback=None, sql=None):
         import codecs
diff --git a/src/calibre/db/notes/connect.py b/src/calibre/db/notes/connect.py
index c226f12936..4398235268 100644
--- a/src/calibre/db/notes/connect.py
+++ b/src/calibre/db/notes/connect.py
@@ -57,8 +57,8 @@ class Notes:
     max_retired_items = 256
 
     def __init__(self, backend):
-        conn = backend.get_connection()
         self.temp_table_counter = count()
+        conn = backend.get_connection()
         libdir = os.path.dirname(os.path.abspath(conn.db_filename('main')))
         self.notes_dir = os.path.join(libdir, NOTES_DIR_NAME)
         self.resources_dir = os.path.join(self.notes_dir, 'resources')
@@ -68,11 +68,17 @@ class Notes:
             os.makedirs(self.notes_dir, exist_ok=True)
             if iswindows:
                 winutil.set_file_attributes(self.notes_dir, winutil.FILE_ATTRIBUTE_HIDDEN | winutil.FILE_ATTRIBUTE_NOT_CONTENT_INDEXED)
-        dbpath = os.path.join(self.notes_dir, 'notes.db')
-        conn.execute("ATTACH DATABASE ? AS notes_db", (dbpath,))
         os.makedirs(self.resources_dir, exist_ok=True)
         os.makedirs(self.backup_dir, exist_ok=True)
         os.makedirs(self.retired_dir, exist_ok=True)
+        self.reopen(backend)
+        for cat in backend.deleted_fields:
+            self.delete_field(conn, cat)
+
+    def reopen(self, backend):
+        conn = backend.get_connection()
+        conn.notes_dbpath = os.path.join(self.notes_dir, 'notes.db')
+        conn.execute("ATTACH DATABASE ? AS notes_db", (conn.notes_dbpath,))
         self.allowed_fields = set()
         triggers = []
         for table in backend.tables.values():
@@ -86,9 +92,6 @@ class Notes:
                 'END;'
             )
         SchemaUpgrade(conn, '\n'.join(triggers))
-        conn.notes_dbpath = dbpath
-        for cat in backend.deleted_fields:
-            self.delete_field(conn, cat)
 
     def delete_field(self, conn, field_name):
         note_ids = conn.get('SELECT id from notes_db.notes WHERE colname=?', (field_name,))
@@ -109,9 +112,10 @@ class Notes:
             resource_hash = resource_hash_or_resource_id
         else:
             resource_hash = conn.get('SELECT hash FROM notes_db.resources WHERE id=?', (resource_hash_or_resource_id,), all=False)
-        idx = resource_hash.index(':')
-        prefix = resource_hash[idx + 1: idx + 3]
-        return os.path.join(self.resources_dir, prefix, resource_hash)
+        hashalg, digest = resource_hash.split(':', 1)
+        prefix = digest[:2]
+        # Cant use colons in filenames on windows safely
+        return os.path.join(self.resources_dir, prefix, f'{hashalg}-{digest}')
 
     def remove_resources(self, conn, note_id, resources_to_potentially_remove, delete_from_link_table=True):
         if not isinstance(resources_to_potentially_remove, tuple):
@@ -310,6 +314,7 @@ class Notes:
         for (name, resource_hash) in conn.execute('SELECT name,hash FROM notes_db.resources WHERE id=?', (resource_id,)):
             path = self.path_for_resource(conn, resource_hash)
             path = make_long_path_useable(path)
+            os.listdir(os.path.dirname(path))
             with suppress(FileNotFoundError), open(path, 'rb') as f:
                 return {'name': name, 'data': f.read(), 'hash': resource_hash}
 
diff --git a/src/calibre/db/tests/filesystem.py b/src/calibre/db/tests/filesystem.py
index 9ffa6ccf88..085e783427 100644
--- a/src/calibre/db/tests/filesystem.py
+++ b/src/calibre/db/tests/filesystem.py
@@ -264,7 +264,6 @@ class FilesystemTest(BaseTest):
                 bookdir = os.path.dirname(ic.format_abspath(1, '__COVER_INTERNAL__'))
                 self.assertEqual('exf', open(os.path.join(bookdir, 'exf')).read())
                 self.assertEqual('recurse', open(os.path.join(bookdir, 'sub', 'recurse')).read())
-                ic.close()
         r1 = cache.add_notes_resource(b'res1', 'res.jpg')
         r2 = cache.add_notes_resource(b'res2', 'res.jpg')
         cache.set_notes_for('authors', 2, 'some notes', resource_ids=(r1, r2))
@@ -287,8 +286,6 @@ class FilesystemTest(BaseTest):
             self.assertEqual(ic.fts_search('exim')[0]['id'], 1)
             self.assertEqual(cache.notes_for('authors', 2), ic.notes_for('authors', 2))
             self.assertEqual(cache.get_notes_resource(r1), ic.get_notes_resource(r1))
-            ic.close()
-        cache.close()
 
     def test_find_books_in_directory(self):
         from calibre.db.adding import find_books_in_directory, compile_rule