Certain rooms in room directory cannot be joined.

[daedric7]

Steps to reproduce

1. Click top search bar
2. Select Rooms
3. Change current server to Libera.chat
4. Type "Mastodon" and wait for the result
5. Click Join

Outcome

What did you expect?

The usual joining (even if slow and with errors) of the room.

What happened instead?

Instant error:

Failed to join

MatrixError: [404] Can't join remote room because no servers that are in the room have been provided. (https://aguiarvieira.pt/_matrix/client/r0/join/!QVGzddUWpPdvanbeBp%3Alibera.chat)

Operating system

Ubuntu running on a Oracle Free Arm.

Application version

versão do Element: 1.11.16 Olm version: 3.2.12

How did you install the app?

Oficial element webpage

Homeserver

aguiarvieira.pt

Will you send logs?

Yes

[daedric7]

result of docker compose logs right after attempting to join the room:

matrix-postgres  | 2022-12-07 22:29:43.759 UTC [36] ERROR:  could not serialize access due to concurrent update
matrix-postgres  | 2022-12-07 22:29:43.759 UTC [36] STATEMENT:  INSERT INTO account_data (user_id, account_data_type, stream_id, content) VALUES ('@daedric:aguiarvieira.pt', 'im.vector.web.settings', 10141, '{"MessageComposerInput.insertTrailingColon":true,"deviceClientInformationOptIn":true,"SpotlightSearch.recentSearches":["!QVGzddUWpPdvanbeBp:libera.chat","!dfclKzOduGNuyuRPZU:libera.chat","!DQJVniaSzEOMrvVSsB:aguiarvieira.pt","!uXvvbgIhuFMCGAIeRR:maunium.net","!rhzvpsUPIYocutzXMf:midov.pl","!CJLYyMYkwPyraCvrRu:midov.pl","!UeTeyNedDrjNKNBMNq:anontier.nl","!EDOCKtRwqSlfrROnqI:libera.chat","!SzcRUxcpYurpoctOzk:matrix.org","!ibrWVedlXMAAFnhIub:matrix.org"],"breadcrumbs":true,"room_directory_servers":["midov.pl","maunium.net"],"Images.size":"large","Spaces.allRoomsInHome":true,"autoplayGifs":true,"autoplayVideo":true,"MessageComposerInput.autoReplaceEmoji":true,"enableSyntaxHighlightLanguageDetection":true,"Spaces.enabledMetaSpaces":{"home-space":true,"people-space":true,"favourites-space":true,"orphans-space":true}}') ON CONFLICT (user_id, account_data_type)  DO UPDATE SET stream_id=EXCLUDED.stream_id, content=EXCLUDED.content
matrix-synapse   | 2022-12-07 22:29:43,760 - synapse.storage.txn - 717 - WARNING - PUT-219506 - [TXN OPERROR] {add_user_account_data-125b14} could not serialize access due to concurrent update
matrix-synapse   |  0/5

[richvdh]

I was able to repeat this. E-W sent a /join request: POST https://matrix.sw1v.org/_matrix/client/r0/join/!QVGzddUWpPdvanbeBp%3Alibera.chat with a body of {}. Note the absence of server name in the request.

Synapse logs:

2022-12-07 22:12:49,013 - synapse.http.server - 108 - INFO - POST-1331 - <XForwardedForRequest at 0x7f9161d57898 method='POST' uri='/_matrix/client/r0/join/!QVGzddUWpPdvanbeBp%3Alibera.chat' clientproto='HTTP/1.0' site='8008'> SynapseError: 404 - Can't join remote room because no servers that are in the room have been provided.
2022-12-07 22:12:49,019 - synapse.access.http.8008 - 481 - INFO - POST-1331 - 2001:8b0:ba7a:e98f:4ddd:69b1:9dd:7564 - 8008 - {@richvdh:sw1v.org} Processed request: 0.007sec/0.006sec (0.006sec, 0.000sec) (0.001sec/0.003sec/4) 116B 404 "POST /_matrix/client/r0/join/!QVGzddUWpPdvanbeBp%3Alibera.chat HTTP/1.0" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Element-Nightly/2022112501 Chrome/106.0.5249.181 Electron/21.3.0 Safari/537.36" [0 dbevts]

[richvdh]

(I suspect this is not limited to libera.chat)

[t3chguy]

@richvdh where would EW get the server name from? It can't know for a fact that the server giving it room directory results is actually still in the room.

[richvdh]

Good question I guess, though I'm pretty sure the intention of the federation /publicRooms API is that servers should not return rooms they have left.

I've raised matrix-org/matrix-spec#1375 to track the clarification anyway.

[t3chguy]

Blocked on spec clarification

[0xb1b1]

Can reproduce. Error details below:

Error message box

MatrixError: [404] Can't join remote room because no servers that are in the room have been provided. (https://[redacted]/_matrix/client/r0/join/!JlytvgrOTrGPXOfjrK%3Atechlore.net)

Room: Techlore - Main (!JlytvgrOTrGPXOfjrK:techlore.net) (found on matrix.org homeserver)

Deployment details:
Platform: Docker / GNU/Linux NixOS 22.05
Version: matrixdotorg/synapse:v1.75.0 + postgres:alpine3.15
Proxy: Traefik

Some rooms are not "joinable", others (for example, #spitetech:matrix.org) are working fine.

[Happyfeet01]

Can reproduce:

MatrixError: [404] Can't join remote room because no servers that are in the room have been provided. (https://[redacted]/_matrix/client/r0/join/!PukFFdIcHgtaaHZflT%3Adevture.com)

Room Name: Docker + Ansible = Matrix

System: Docker / Debian 11
Synapse 1.76.0
Proxy: Nginx

[JeanPaulLucien]

Meanwhile Matrix's Synapse side has started to suspect something: matrix-org/synapse#15115

[t3chguy]

Given this is biting more people, moving ahead with a fix which assumes matrix-org/matrix-spec#1375 will result in a spec clarification stating that servers must not return rooms they cannot facilitate a join to