Thanks for the reply. But it does not happen to all users. It happens to some users in a user group. The clusters are fine. No errors in the cluster logs. The notebook is in fact not attached to any cluster.

Same issue here, just tried to get set up with community edition but no luck

Even I am facing the same issue. It always keep saying, opening the notepad. Luckily once it is opened and when connected with the cluster, then its getting timeout.