diff --git a/telethon/errors.py b/telethon/errors.py
index cb4fbafe..d48bfe08 100644
--- a/telethon/errors.py
+++ b/telethon/errors.py
@@ -142,6 +142,10 @@ class RPCError(Exception):
         'CHANNEL_INVALID':
         'Invalid channel object. Make sure to pass the right types.',
         'MESSAGE_ID_INVALID': 'The specified message ID is invalid.',
+        'CONNECTION_LAYER_INVALID':
+        'The very first request must always be InvokeWithLayerRequest.',
+        'INPUT_METHOD_INVALID':
+        'The invoked method does not exist anymore or has never existed.',
 
         # 401 UNAUTHORIZED
         'AUTH_KEY_UNREGISTERED': 'The key is not registered in the system.',
diff --git a/telethon/telegram_client.py b/telethon/telegram_client.py
index fe72a8c8..85f464fb 100644
--- a/telethon/telegram_client.py
+++ b/telethon/telegram_client.py
@@ -39,7 +39,7 @@ from .utils import (find_user_or_chat, get_input_peer,
 class TelegramClient:
 
     # Current TelegramClient version
-    __version__ = '0.9'
+    __version__ = '0.9.1'
 
     # region Initialization