diff --git a/pyrogram/session/session.py b/pyrogram/session/session.py
index 686531e3..cf92bcf3 100644
--- a/pyrogram/session/session.py
+++ b/pyrogram/session/session.py
@@ -29,7 +29,7 @@ from pyrogram import __copyright__, __license__, __version__
 from pyrogram import raw
 from pyrogram.connection import Connection
 from pyrogram.crypto import mtproto
-from pyrogram.errors import RPCError, InternalServerError, AuthKeyDuplicated, FloodWait
+from pyrogram.errors import RPCError, InternalServerError, AuthKeyDuplicated, FloodWait, ServiceUnavailable
 from pyrogram.raw.all import layer
 from pyrogram.raw.core import TLObject, MsgContainer, Int, FutureSalt, FutureSalts
 from .internals import MsgId, MsgFactory
@@ -432,7 +432,7 @@ class Session:
                 log.warning(f'[{self.client.session_name}] Sleeping for {amount}s (required by "{query}")')
 
                 await asyncio.sleep(amount)
-            except (OSError, TimeoutError, InternalServerError) as e:
+            except (OSError, TimeoutError, InternalServerError, ServiceUnavailable) as e:
                 if retries == 0:
                     raise e from None