diff --git a/INSTALL.md b/INSTALL.md
index 9b7360f0ef..9da2e3c734 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -109,8 +109,8 @@ Installing prerequisites on Ubuntu or Debian:
 
 ```
 sudo apt-get install build-essential python3-dev libffi-dev \
-                     python-pip python-setuptools sqlite3 \
-                     libssl-dev python-virtualenv libjpeg-dev libxslt1-dev
+                     python3-pip python3-setuptools sqlite3 \
+                     libssl-dev python3-virtualenv libjpeg-dev libxslt1-dev
 ```
 
 #### ArchLinux
diff --git a/changelog.d/6237.bugfix b/changelog.d/6237.bugfix
new file mode 100644
index 0000000000..9285600b00
--- /dev/null
+++ b/changelog.d/6237.bugfix
@@ -0,0 +1 @@
+Transfer non-standard power levels on room upgrade.
\ No newline at end of file
diff --git a/changelog.d/6241.bugfix b/changelog.d/6241.bugfix
new file mode 100644
index 0000000000..25109ca4a6
--- /dev/null
+++ b/changelog.d/6241.bugfix
@@ -0,0 +1 @@
+Fix error from the Pillow library when uploading RGBA images.
diff --git a/changelog.d/6443.doc b/changelog.d/6443.doc
new file mode 100644
index 0000000000..67c59f92ee
--- /dev/null
+++ b/changelog.d/6443.doc
@@ -0,0 +1 @@
+Switch Ubuntu package install recommendation to use python3 packages in INSTALL.md.
\ No newline at end of file
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index e92b2eafd5..35a759f2fe 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -198,21 +198,21 @@ class RoomCreationHandler(BaseHandler):
         # finally, shut down the PLs in the old room, and update them in the new
         # room.
         yield self._update_upgraded_room_pls(
-            requester, old_room_id, new_room_id, old_room_state
+            requester, old_room_id, new_room_id, old_room_state,
         )
 
         return new_room_id
 
     @defer.inlineCallbacks
     def _update_upgraded_room_pls(
-        self, requester, old_room_id, new_room_id, old_room_state
+        self, requester, old_room_id, new_room_id, old_room_state,
     ):
         """Send updated power levels in both rooms after an upgrade
 
         Args:
             requester (synapse.types.Requester): the user requesting the upgrade
-            old_room_id (unicode): the id of the room to be replaced
-            new_room_id (unicode): the id of the replacement room
+            old_room_id (str): the id of the room to be replaced
+            new_room_id (str): the id of the replacement room
             old_room_state (dict[tuple[str, str], str]): the state map for the old room
 
         Returns:
@@ -298,7 +298,7 @@ class RoomCreationHandler(BaseHandler):
             tombstone_event_id (unicode|str): the ID of the tombstone event in the old
                 room.
         Returns:
-            Deferred[None]
+            Deferred
         """
         user_id = requester.user.to_string()
 
@@ -333,6 +333,7 @@ class RoomCreationHandler(BaseHandler):
             (EventTypes.Encryption, ""),
             (EventTypes.ServerACL, ""),
             (EventTypes.RelatedGroups, ""),
+            (EventTypes.PowerLevels, ""),
         )
 
         old_room_state_ids = yield self.store.get_filtered_current_state_ids(
@@ -346,6 +347,31 @@ class RoomCreationHandler(BaseHandler):
             if old_event:
                 initial_state[k] = old_event.content
 
+        # Resolve the minimum power level required to send any state event
+        # We will give the upgrading user this power level temporarily (if necessary) such that
+        # they are able to copy all of the state events over, then revert them back to their
+        # original power level afterwards in _update_upgraded_room_pls
+
+        # Copy over user power levels now as this will not be possible with >100PL users once
+        # the room has been created
+
+        power_levels = initial_state[(EventTypes.PowerLevels, "")]
+
+        # Calculate the minimum power level needed to clone the room
+        event_power_levels = power_levels.get("events", {})
+        state_default = power_levels.get("state_default", 0)
+        ban = power_levels.get("ban")
+        needed_power_level = max(state_default, ban, max(event_power_levels.values()))
+
+        # Raise the requester's power level in the new room if necessary
+        current_power_level = power_levels["users"][requester.user.to_string()]
+        if current_power_level < needed_power_level:
+            # Assign this power level to the requester
+            power_levels["users"][requester.user.to_string()] = needed_power_level
+
+        # Set the power levels to the modified state
+        initial_state[(EventTypes.PowerLevels, "")] = power_levels
+
         yield self._send_events_for_new_room(
             requester,
             new_room_id,
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py
index 8cf415e29d..c234ea7421 100644
--- a/synapse/rest/media/v1/thumbnailer.py
+++ b/synapse/rest/media/v1/thumbnailer.py
@@ -129,5 +129,8 @@ class Thumbnailer(object):
 
     def _encode_image(self, output_image, output_type):
         output_bytes_io = BytesIO()
-        output_image.save(output_bytes_io, self.FORMATS[output_type], quality=80)
+        fmt = self.FORMATS[output_type]
+        if fmt == "JPEG":
+            output_image = output_image.convert("RGB")
+        output_image.save(output_bytes_io, fmt, quality=80)
         return output_bytes_io