Upgrading a room (to v11?) produces an invalid `m.room.create` event

[pixlwave]

Description

We've had a report of Element iOS crashing when opening rooms that are v11 (element-hq/element-ios#7633). I've tracked this down to the room's m.room.create event missing the creator string. The spec seems to indicate that this is a required property.

Steps to reproduce

• Open an existing room (not v11) in Element Web.
• Send /upgrade 11 into to the room to upgrade it.
• Open the devtools and inspect the m.room.create event.
• Notice the required creator field isn't present.

Homeserver

matrix.org

Synapse Version

{"server_version":"1.89.0rc1 (b=matrix-org-hotfixes,42ec11ae56)","python_version":"3.11.4"}

Installation Method

I don't know

Database

I don't know

Workers

I don't know

Platform

I don't know

Configuration

No response

Relevant log output

An upgraded room:


{
  "content": {
    "predecessor": {
      "event_id": "$T0Ufk2Egroh__UEYLJTlDij6ocRnr8De-GGKXtJfD2k",
      "room_id": "!WKiEIISPfQzUiDJzhS:matrix.org"
    },
    "room_version": "11"
  },
  "origin_server_ts": 1690970761964,
  "sender": "@iosdevsim:matrix.org",
  "state_key": "",
  "type": "m.room.create",
  "unsigned": {
    "age": 441
  },
  "event_id": "$6aoB9WDmdkN_qxRzq2nde0x5M8F1aKdey0xZ4WeqMsI",
  "room_id": "!OGmXOlBGeoyILdDDkh:matrix.org"
}

### Anything else that would be useful to know?

Just for comparison, here's a create event for a v9 room

{
"content": {
"creator": "@iosdevsim:matrix.org",
"room_version": "9"
},
"origin_server_ts": 1669825203254,
"sender": "@iosdevsim:matrix.org",
"state_key": "",
"type": "m.room.create",
"unsigned": {
"age": 21145236426
},
"event_id": "$d5jYmLHlk3yzz0isn8mL9QpRa87isjUA-35zmtcRQeg",
"room_id": "!YCpieHsogoKpVyPLWg:matrix.org"
}

[pixlwave]

Also adding that the same room on Element X shows an unsupported event error:

[clokep]

Room version 11 no longer has a creator property, see MSC2175. (The in-progress spec PR can be viewed at https://pr1604--matrix-spec-previews.netlify.app/rooms/v11/).

[clokep]

(CC @turt2live -- hopefully this isn't a widespread issue for clients.)

[pixlwave]

Ah ok, that makes sense now. Thanks 👍