diff --git a/mercurial/utils/resourceutil.py b/mercurial/utils/resourceutil.py
--- a/mercurial/utils/resourceutil.py
+++ b/mercurial/utils/resourceutil.py
@@ -64,11 +64,6 @@
     # Force loading of the resources module
     resources.open_binary  # pytype: disable=module-attr
 
-    # pytype: disable=import-error
-    from importlib.resources import FileNotFoundError
-
-    # pytype: enable=import-error
-
     def open_resource(package, name):
         return resources.open_binary(  # pytype: disable=module-attr
             pycompat.sysstr(package), pycompat.sysstr(name)
@@ -90,9 +85,6 @@
     # importlib.resources was not found (almost definitely because we're on a
     # Python version before 3.7)
 
-    class FileNotFoundError(RuntimeError):
-        pass
-
     def open_resource(package, name):
         path = os.path.join(_package_path(package), name)
         return open(path, "rb")