Trying to rejoin a local empty room gives a 500 error

[ChazyTheBest]

In a quick setup of my custom server I tried the following and got an error:

• Create a new room
• Leave
• Try to join again
• Internal server error (M_UNKNOWN)

With both the web client and riot.im. But the room still exists, and I can see the history (only using riot.im, the synapse web client redirects to home).

[richvdh]

@ChazyTheBest when I do this, I don't get an internal server error; I get a 404 with:

{"errcode":"M_UNKNOWN","error":"No known servers"}

This is somewhat expected, as per https://github.com/vector-im/riot-web/issues/1194, https://github.com/matrix-org/matrix-doc/issues/534, and #1533.

If you're actually seeing an internal server error, could you share logs from your homeserver?

[richvdh]

With both the web client and riot.im.

riot.im is the web client.

[richvdh]

With both the web client and riot.im.

riot.im is the web client.

ohh, you meant the matrix console client. Ignore the last message.

[ChazyTheBest]

No, I meant the synapse web client, the one i can access via https://127.0.0.1:8448. The internal server error is from riot.im

Where are the logs located? I'm not too good with systemd and I think they may be in the journal somewhere.

[richvdh]

The webapp bundled with synapse is called matrix console: http://matrix.org/docs/projects/client/matrix-console.html.

riot.im is just serving static assets; it's very unlikely to be serving an internal server error. Can you share a screenshot?

The synapse logs will be wherever you (or the distribution you use) has configured them to be... check the homeserver.yaml for log_config or log_file; or try journalctl -u synapse to get the logs from the synapse systemd unit. Sorry, it's very hard to guess where they might be. I suggest you come and get support in one of the public matrix rooms if you can't find them.

[ChazyTheBest]

So that's it, sorry I didn't know.

Here's a screenshot of the error and the steps:

From riot.im:

• Create the new room
• Give the room a local address and list it publicly
• Check it's listed and enter again
• Leave room and try to rejoin

The homeserver.yaml file says the log file is in /var/lib/synapse/homeserver.log but it's not there (not created).

[richvdh]

Ok thanks. That looks like synapse is returning an ISE to the join request.

I fear we're not going to get far without the synapse logs.

Worth noting that log_config takes precedence over log_file if both are specified.

[ChazyTheBest]

The *log.config file says the same: filename: /var/lib/synapse/homeserver.log.

I'll join the matrix room tomorrow to ask how to get the logs.

[richvdh]

if you get the logs let us know and we can reopen this

[david-austin]

I just ran into this Problem yesterday and want to share my log:
matrix_synapse_exception.log

I used the docker image from Silvio to install a Synapse server and did just the same thing:

• create a new room
• leave
• try to join again

If you need any further information let me know

[edwinbalani]

@richvdh I have been able to reproduce this issue, using a different environment from what @david-austin has (details below).

Description

Unable to join a room that contains no members. The homeserver returns HTTP 500 (internal server error) to the join request.

The room used to reproduce this belonged to the same homeserver to which I was connected.

Steps to reproduce

1. Create a room (in this example, #test-public:_redacted_.example.com), make it joinable by all
2. Leave the room, meaning it has no members
3. Attempt to join the room again

• Result: server returns code 500.
• Client behaviour:
  • riot-web shows a modal entitled "Failed to join room", with the message "Internal server error"
  • This Weechat client logs HTTP API returned error. Code: 500, reason: Internal Server Error

homeserver.log

2018-04-08 22:29:40,829 - synapse.http.server - 191 - ERROR - POST-3- Failed handle request synapse.http.server._async_render on <synapse.rest.ClientRestResource object at 0x7f118ccd4fd0>: <XForwardedForRequest 
at 0x7f118c192b90 method=POST uri=/_matrix/client/r0/join/%23test-public%3A_redacted_.example.com?access_token=<redacted> clientproto=HTTP/1.0 site=8008>: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1445, in unwindGenerator
    return _inlineCallbacks(None, gen, Deferred())
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1299, in _inlineCallbacks
    result = g.send(result)
  File "/usr/lib/python2.7/dist-packages/synapse/handlers/federation.py", line 1199, in _make_and_verify_event
    content,
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1445, in unwindGenerator
    return _inlineCallbacks(None, gen, Deferred())
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 1299, in _inlineCallbacks
    result = g.send(result)
  File "/usr/lib/python2.7/dist-packages/synapse/federation/federation_client.py", line 536, in make_membership_event
    raise RuntimeError("Failed to send to any server.")
exceptions.RuntimeError: Failed to send to any server.

Environment information

• Homeserver: Own Synapse homeserver. Hostname is the same as Matrix 'server name', in both cases I've changed it to _redacted_.example.com here, as the homeserver is a private one.
• Version: 0.27.2
• Install method: apt, from Debian repo at https://matrix.org/packages/debian/
• Platform: Debian 9.4 Stretch, running in an Amazon EC2 t2.micro instance.
• Networking:
  • Port 8008 is proxied behind nginx on 443, but port 8448 goes directly to the Synapse daemon.
  • The request in this case came in on 443 and was forwarded by nginx to Synapse.
  • Both IPv4 and IPv6 in use.

[ara4n]

This is https://github.com/matrix-org/matrix-doc/issues/534. Thanks for the comprehensive bug report, but the best bet is to upvote that one instead.

[edwinbalani]

Thanks for the heads-up @ara4n; I was posting here mainly because of this:

when I do this, I don't get an internal server error; I get a 404
If you're actually seeing an internal server error, could you share logs from your homeserver?

And I've reproduced this -- i.e. not getting 404 but 500, which seems to be a deviation from what's expected.

[richvdh]

thanks for the reports. It looks like we return a 500 when the room alias is on the local server.