# WebSockets issue! **URL:** \ **Category:** Uncategorized\ **Created:** [March 2, 2023, 12:09am UTC](https://community.dremio.com/t/websockets-issue/10344 "2023-03-02T00:09:38Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![balaji.ramaswamy](https://sea2.discourse-cdn.com/flex020/user_avatar/community.dremio.com/balaji.ramaswamy/32/843_2.png) [@balaji.ramaswamy](https://community.dremio.com/u/balaji.ramaswamy)\ **Post date:** [March 6, 2023, 5:03am UTC](https://community.dremio.com/t/websockets-issue/10344/2 "2023-03-06T05:03:46Z")
@sulemanb Have you looked at these posts, usually a rule missing in your network > [@Websockets errors: ELB issue or symptom of something else?](https://community.dremio.com/t/websockets-errors-elb-issue-or-symptom-of-something-else/6623/2): > > @fizz Ensuring that your environment allows WebSocket communication is a requirement, are you saying even after doing the same you are getting the above websocket error? > [@Issue communicating with Dremio](https://community.dremio.com/t/issue-communicating-with-dremio/1995): > > Hello! We have Dremio running on a server and this error always comes up in Dremio’s UI: There was an issue communicating with Dremio. show less Your Internet connection may be offline, or WebSockets to Dremio are being blocked. It does not seem to affect the functioning of Dremio (one can still log in, run queries, save views, etc.), however it would be nice to understand where does it come from and how to fix it. Thank you! > [@\[Fixed\] Unable to start worker nodes](https://community.dremio.com/t/fixed-unable-to-start-worker-nodes/2305): > > I setup a 4 node (2 co-ordinator 1 master, 1 non master on md5.2xl; and 2 executor on md5.4xl) dremio cluster with embedded zk, which was up and running fine. I tried stopping and starting the dremio daemon and now I’m getting the following error: Exception in thread "main" java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936) at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:964) at com.dremio.datastore.ReIndexer.isI… > **[System Requirements | Dremio Documentation](https://docs.dremio.com/current/get-started/cluster-deployments/deployment-models/standalone/system-requirements/)** > > This topic covers system requirements for standalone clusters including general requirements for Hadoop on YARN and MapR on YARN deployments. --- _[View the full topic](https://community.dremio.com/t/websockets-issue/10344)._