Hi all,
when conducting data collections with oTree on Heroku, we see a lot of errors like the one below:
"OSError: [Errno 107] Transport endpoint is not connected"
From my understanding, this error happens when the connection to a respondent drops during the communication between the server and the client, e.g. the client closes the browser tab or loses internet connection. 
Therefore, I don't pay much attention to this error, because we can always expect some participants to drop out.
Is my interpretation of the cause of this error correct?
Best regards
Jakob


Mar 06 10:49:29  xyz-x app/web.1 INFO:     XX.XXX.XXX.XXX:0 - "GET /p/gopvl7pq/stdy_2_at/PageWel2/127 HTTP/1.1" 200 OK
Mar 06 10:49:29  xyz-x app/web.1 closing handshake failed
Mar 06 10:49:29  xyz-x app/web.1 Traceback (most recent call last):
Mar 06 10:49:29  xyz-x app/web.1   File "/app/.heroku/python/lib/python3.9/site-packages/websockets/legacy/server.py", line 239, in handler
Mar 06 10:49:29  xyz-x app/web.1     await self.close()
Mar 06 10:49:29  xyz-x app/web.1   File "/app/.heroku/python/lib/python3.9/site-packages/websockets/legacy/protocol.py", line 779, in close
Mar 06 10:49:29  xyz-x app/web.1     await asyncio.shield(self.close_connection_task)
Mar 06 10:49:29  xyz-x app/web.1   File "/app/.heroku/python/lib/python3.9/site-packages/websockets/legacy/protocol.py", line 1309, in close_connection
Mar 06 10:49:29  xyz-x app/web.1     self.transport.write_eof()
Mar 06 10:49:29  xyz-x app/web.1   File "/app/.heroku/python/lib/python3.9/asyncio/selector_events.py", line 970, in write_eof
Mar 06 10:49:29  xyz-x app/web.1     self._sock.shutdown(socket.SHUT_WR)
Mar 06 10:49:29  xyz-x app/web.1 OSError: [Errno 107] Transport endpoint is not connected

I think this is one of the errors that can be ignored.

Thanks for giving me peace of mind on this :)