Why am I getting the "Spawn Failed: Server at http://127.0.0.1:47353/user/fyicenter/ didn't respond in 30 seconds"?

If you did not install or configure JupyterHub correctly, you will get the following error after user logs in on the Web interface.

Spawn Failed: Server at 
http://127.0.0.1:47353/user/fyicenter/ didn't respond in 30 seconds

If you look at the JupyterHub server log, you may see these messages:

[I JupyterHub log] 302 GET / -> /hub/ (@::1) 0.71ms
[I JupyterHub log] 302 GET /hub/ -> /hub/login?next=%2Fhub%2F (@::1) 0.54ms
[I JupyterHub log] 200 GET /hub/login?next=%2Fhub%2F (@::1) 320.74ms

[ConfigProxy] error: 503 GET /hub/static/components/font-awesome/fonts/fontawesome-webfont.woff2 socket hang up

[I JupyterHub log] 200 GET /hub/error/503?url=%2Fhub%2Fstatic%2Fcomponents%2Ffont-awesome%2Ffonts%2Ffontawesome-webfont.woff2%3Fv%3D4.7.0 (@127.0.0.1) 37.81ms
[I JupyterHub base] User logged in: fyicenter
[I JupyterHub log] 302 POST /hub/login?next=%2Fhub%2F -> /hub/ (fyicenter@::1) 428.87ms
[I JupyterHub log] 302 GET /hub/ -> /hub/spawn (fyicenter@::1) 67.52ms
[I JupyterHub provider] Creating oauth client jupyterhub-user-fyicenter
[I JupyterHub spawner] Spawning jupyterhub-singleuser --port=36703

Failed to set groups [Errno 1] Operation not permitted

[I JupyterHub log:189] 302 GET /hub/spawn -> /hub/spawn-pending/fyicenter (fyicenter@::1) 1338.38ms
[I JupyterHub pages:402] fyicenter is pending spawn
[I JupyterHub log:189] 200 GET /hub/spawn-pending/fyicenter (fyicenter@::1) 101.21ms
[W SingleUserNotebookApp configurable:190] Config option `open_browser` not recognized by `SingleUserNotebookApp`.  Did you mean `browser`?
[I SingleUserNotebookApp mixins:576] Starting jupyterhub-singleuser server version 1.4.2
[I JupyterHub log:189] 200 GET /hub/api (@127.0.0.1) 0.48ms
[I SingleUserNotebookApp notebookapp:2302] Serving notebooks from local directory: /data/jupyter
[I SingleUserNotebookApp notebookapp:2302] Jupyter Notebook 6.4.3 is running at:
[I SingleUserNotebookApp notebookapp:2302] http://192.168.1.200:36703/user/fyicenter/
[I SingleUserNotebookApp notebookapp:2303] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[I SingleUserNotebookApp mixins:556] Updating Hub with activity every 300 seconds
[I JupyterHub log:189] 200 POST /hub/api/users/fyicenter/activity (fyicenter@127.0.0.1) 835.82ms
[W JupyterHub base:1040] User fyicenter is slow to become responsive (timeout=10)

[W JupyterHub user:767] fyicenter's server never showed up at http://127.0.0.1:36703/user/fyicenter/ after 30 seconds. Giving up

[I SingleUserNotebookApp notebookapp:2139] Shutting down 0 kernels
[I SingleUserNotebookApp notebookapp:2154] Shutting down 0 terminals
[I JupyterHub log] 200 GET /hub/api/users/fyicenter/server/progress (fyicenter@::1) 27207.66ms

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