diff --git a/mautrix_telegram/commands/matrix_auth.py b/mautrix_telegram/commands/matrix_auth.py
index 5cc00f01..6fca9f6b 100644
--- a/mautrix_telegram/commands/matrix_auth.py
+++ b/mautrix_telegram/commands/matrix_auth.py
@@ -81,6 +81,21 @@ async def ping_matrix(evt: CommandEvent) -> EventID:
     return await evt.reply("Your Matrix login is working.")
 
 
+@command_handler(needs_auth=True, needs_matrix_puppeting=True, help_section=SECTION_AUTH,
+                 help_text="Clear the Matrix sync token stored for your custom puppet.")
+async def clear_cache_matrix(evt: CommandEvent) -> EventID:
+    puppet = pu.Puppet.get(evt.sender.tgid)
+    if not puppet.is_real_user:
+        return await evt.reply("You are not logged in with your Matrix account.")
+    try:
+        puppet.stop()
+        puppet.next_batch = None
+        await puppet.start()
+    except InvalidAccessToken:
+        return await evt.reply("Your access token is invalid.")
+    return await evt.reply("Cleared cache successfully.")
+
+
 async def enter_matrix_token(evt: CommandEvent) -> EventID:
     evt.sender.command_status = None
 
diff --git a/mautrix_telegram/commands/telegram/misc.py b/mautrix_telegram/commands/telegram/misc.py
index 873de207..60b12181 100644
--- a/mautrix_telegram/commands/telegram/misc.py
+++ b/mautrix_telegram/commands/telegram/misc.py
@@ -14,12 +14,13 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 from typing import List, Optional, Tuple
+import logging
 import codecs
 import base64
 import re
 
 from telethon.errors import (InviteHashInvalidError, InviteHashExpiredError, OptionsTooMuchError,
-                             UserAlreadyParticipantError)
+                             UserAlreadyParticipantError, ChatIdInvalidError)
 from telethon.tl.patched import Message
 from telethon.tl.types import (User as TLUser, TypeUpdates, MessageMediaGame, MessageMediaPoll,
                                TypePeer)
@@ -143,7 +144,11 @@ async def join(evt: CommandEvent) -> Optional[EventID]:
             return await evt.reply(f"Invited you to portal of {portal.title}")
         else:
             await evt.reply(f"Creating room for {chat.title}... This might take a while.")
-            await portal.create_matrix_room(evt.sender, chat, [evt.sender.mxid])
+            try:
+                await portal.create_matrix_room(evt.sender, chat, [evt.sender.mxid])
+            except ChatIdInvalidError as e:
+                logging.getLogger("mau.commands").info(updates.stringify())
+                raise e
             return await evt.reply(f"Created room for {portal.title}")
     return None
 
diff --git a/mautrix_telegram/portal/metadata.py b/mautrix_telegram/portal/metadata.py
index 6d1f0563..0b56d143 100644
--- a/mautrix_telegram/portal/metadata.py
+++ b/mautrix_telegram/portal/metadata.py
@@ -545,7 +545,8 @@ class PortalMetadata(BasePortal, ABC):
             await self.main_intent.remove_room_alias(self._get_alias_localpart())
         self.username = username or None
         if self.username:
-            await self.main_intent.add_room_alias(self.mxid, self._get_alias_localpart())
+            await self.main_intent.add_room_alias(self.mxid, self._get_alias_localpart(),
+                                                  override=True)
             if self.public_portals:
                 await self.main_intent.set_join_rule(self.mxid, "public")
         else: