diff --git a/src/borg/archiver.py b/src/borg/archiver.py
index 6e31e9dd4..fe6840039 100644
--- a/src/borg/archiver.py
+++ b/src/borg/archiver.py
@@ -88,7 +88,6 @@ try:
     from .remote import RepositoryServer, RemoteRepository, cache_if_remote
     from .repository import Repository, LIST_SCAN_LIMIT, TAG_PUT, TAG_DELETE, TAG_COMMIT
     from .selftest import selftest
-    from .upgrader import BorgRepositoryUpgrader
 except BaseException:
     # an unhandled exception in the try-block would cause the borg cli command to exit with rc 1 due to python's
     # default behavior, see issue #4424.
diff --git a/src/borg/upgrader.py b/src/borg/upgrader.py
index 68e4c6af5..e69de29bb 100644
--- a/src/borg/upgrader.py
+++ b/src/borg/upgrader.py
@@ -1,56 +0,0 @@
-import os
-
-from .crypto.key import KeyfileKey, KeyfileNotFoundError
-from .helpers import get_base_dir, get_keys_dir
-from .logger import create_logger
-from .repository import Repository
-
-logger = create_logger(__name__)
-
-
-class BorgRepositoryUpgrader(Repository):
-    def upgrade(self, dryrun=True, inplace=False, progress=False):
-        """convert an old borg repository to a current borg repository
-        """
-        logger.info("converting borg 0.xx to borg current")
-        with self:
-            try:
-                keyfile = self.find_borg0xx_keyfile()
-            except KeyfileNotFoundError:
-                logger.warning("no key file found for repository")
-            else:
-                self.move_keyfiles(keyfile, dryrun)
-
-    def find_borg0xx_keyfile(self):
-        return Borg0xxKeyfileKey.find_key_file(self)
-
-    def move_keyfiles(self, keyfile, dryrun):
-        filename = os.path.basename(keyfile)
-        new_keyfile = os.path.join(get_keys_dir(), filename)
-        try:
-            os.rename(keyfile, new_keyfile)
-        except FileExistsError:
-            pass
-
-
-class Borg0xxKeyfileKey(KeyfileKey):
-    """backwards compatible borg 0.xx key file parser"""
-
-    @staticmethod
-    def get_keys_dir():
-        return os.environ.get('BORG_KEYS_DIR',
-                              os.path.join(get_base_dir(), '.borg', 'keys'))
-
-    @classmethod
-    def find_key_file(cls, repository):
-        get_keys_dir = cls.get_keys_dir
-        keys_dir = get_keys_dir()
-        if not os.path.exists(keys_dir):
-            raise KeyfileNotFoundError(repository.path, keys_dir)
-        for name in os.listdir(keys_dir):
-            filename = os.path.join(keys_dir, name)
-            with open(filename) as fd:
-                line = fd.readline().strip()
-                if line and line.startswith(cls.FILE_ID) and line[len(cls.FILE_ID) + 1:] == repository.id_str:
-                    return filename
-        raise KeyfileNotFoundError(repository.path, keys_dir)