BAD GATEWAY when I try to join a room #2957

2018-03-06 12:14:31,666 - synapse.access.http.8008 - 59 - INFO - GET-434- - - 8008 - Received request: GET /_matrix/client/api/v1/directory/room/%23matrix-dev%3Amatrix.org
2018-03-06 12:14:31,668 - synapse.http.outbound - 154 - INFO - GET-434- {GET-O-12} [matrix.org] Sending request: GET matrix://matrix.org/_matrix/federation/v1/query/directory?room_alias=%23matrix-dev%3Amatrix.org
2018-03-06 12:14:32,797 - synapse.handlers.typing - 78 - INFO - - Checking for typing timeouts
2018-03-06 12:14:32,797 - synapse.handlers.presence - 327 - INFO - - Handling presence timeouts
2018-03-06 12:14:32,873 - synapse.storage.TIME - 213 - INFO - - Total database time: 0.004% {get_destination_retry_timings(1): 0.003%, _update_client_ips_batch(2): 0.001%, who_forgot(0): 0.000%} {}
2018-03-06 12:14:37,796 - synapse.handlers.typing - 78 - INFO - - Checking for typing timeouts
2018-03-06 12:14:37,797 - synapse.handlers.presence - 327 - INFO - - Handling presence timeouts
2018-03-06 12:14:42,795 - synapse.handlers.typing - 78 - INFO - - Checking for typing timeouts
2018-03-06 12:14:42,797 - synapse.handlers.presence - 327 - INFO - - Handling presence timeouts
2018-03-06 12:14:42,872 - synapse.storage.TIME - 213 - INFO - - Total database time: 0.001% {_update_client_ips_batch(2): 0.001%, who_forgot(0): 0.000%, update_user_directory_stream_pos(0): 0.000%} {}
2018-03-06 12:14:42,899 - synapse.http.outbound - 236 - INFO - GET-434- {GET-O-12} [matrix.org] Result: 502 Bad Gateway
2018-03-06 12:14:42,900 - root - 188 - WARNING - GET-434- Error retrieving alias
2018-03-06 12:14:42,902 - synapse.http.server - 127 - ERROR - GET-434- 502: Bad Gateway
Traceback (most recent call last):
  File "/root/.synapse/lib/python2.7/site-packages/synapse/http/server.py", line 117, in wrapped_request_handler
    yield request_handler(self, request, request_metrics)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/http/server.py", line 263, in _async_render
    callback_return = yield callback(request, **kwargs)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/rest/client/v1/directory.py", line 50, in on_GET
    res = yield dir_handler.get_association(room_alias)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/handlers/directory.py", line 185, in get_association
    ignore_backoff=True,
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/federation/transport/client.py", line 188, in make_query
    ignore_backoff=ignore_backoff,
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1384, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/root/.synapse/lib/python2.7/site-packages/twisted/python/failure.py", line 408, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/http/matrixfederationclient.py", line 442, in get_json
    ignore_backoff=ignore_backoff,
  File "/root/.synapse/lib/python2.7/site-packages/twisted/internet/defer.py", line 1386, in _inlineCallbacks
    result = g.send(result)
  File "/root/.synapse/lib/python2.7/site-packages/synapse/http/matrixfederationclient.py", line 247, in _request
    response.code, response.phrase, body
HttpResponseException: 502: Bad Gateway

worker_processes  1;
events {
    worker_connections  1024;
}
http {
    include       mime.types;
    default_type  application/octet-stream;

    sendfile        on;
    keepalive_timeout  65;

    server {
        listen 80;
        server_name localhost;

        location /_matrix {
            proxy_pass http://localhost:8008;
            proxy_set_header X-Forwarded-For $remote_addr;
        }
   }
}