I'm having the same exact problem, and clearing the cache doesn't solve it. I tried with different browsers.
Command Line Output
[Voila] Looking for voila in /etc/jupyter
[Voila] Looking for voila in /usr/local/etc/jupyter
[Voila] Looking for voila in /usr/etc/jupyter
[Voila] Looking for voila in /home/myuser/.local/etc/jupyter
[Voila] Looking for voila in /home/myuser/.jupyter
[Voila] Looking for voila in /home/myuser/Documenti/network_analysis
[Voila] using template: lab
[Voila] template paths:
/usr/share/jupyter/voila/templates/lab
/usr/share/jupyter/nbconvert/templates/lab
/usr/share/jupyter/voila/templates/base
/usr/share/jupyter/nbconvert/templates/base
/home/myuser/.local/share/jupyter
/home/myuser/.local/share/jupyter/voila/templates
/home/myuser/.local/share/jupyter/nbconvert/templates
/usr/share/jupyter
/usr/share/jupyter/voila/templates
/usr/share/jupyter/nbconvert/templates
[Voila] static paths:
/home/myuser/.local/share/jupyter/voila/templates/lab/static
/home/myuser/.local/share/jupyter/nbconvert/templates/lab/static
/usr/share/jupyter/voila/templates/lab/static
/usr/share/jupyter/nbconvert/templates/lab/static
/home/myuser/.local/share/jupyter/voila/templates/base/static
/home/myuser/.local/share/jupyter/nbconvert/templates/base/static
/usr/share/jupyter/voila/templates/base/static
/usr/share/jupyter/nbconvert/templates/base/static
/usr/lib/python3.13/site-packages/jupyter_server/static
[Voila] Using /tmp to store connection files
[Voila] Storing connection files in /tmp/voila_8y9yhj1l.
[Voila] Serving static files from /usr/lib/python3.13/site-packages/voila/static.
[Voila] Voilà is running at:
http://localhost:8866/
[Voila] WARNING | Clearing invalid/expired login cookie username-localhost-8866
[Voila] Generating new user for token-authenticated request: 5dd9495ee8dc41d18a6b7a6e3b8bcb85
[Voila] Paths used for configuration of page_config:
/etc/jupyter/labconfig/page_config.json
[Voila] Paths used for configuration of page_config:
/usr/local/etc/jupyter/labconfig/page_config.json
[Voila] Paths used for configuration of page_config:
/usr/etc/jupyter/labconfig/page_config.json
[Voila] Paths used for configuration of page_config:
/home/myuser/.local/etc/jupyter/labconfig/page_config.json
[Voila] Paths used for configuration of page_config:
/home/myuser/.jupyter/labconfig/page_config.json
[Voila] WARNING | Notebook cosmograph_visualize.ipynb is not trusted
[Voila] Found kernel python3 in /usr/share/jupyter/kernels
[Voila] Found kernel sagemath in /usr/share/jupyter/kernels
[Voila] Instantiating kernel 'Python 3 (ipykernel)' with kernel provisioner: local-provisioner
[Voila] Starting kernel: ['/usr/bin/python', '-m', 'ipykernel_launcher', '-f', '/tmp/voila_8y9yhj1l/kernel-63762c06-5ddf-4849-856b-f8529d6926de.json']
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Kernel started: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Kernel args (excluding env): {'kernel_name': 'python3', 'cwd': '/home/myuser/Documenti/network_analysis'}
[Voila] Kernel argument 'env' passed with: ['SHELL', 'SESSION_MANAGER', 'CAML_LD_LIBRARY_PATH', 'OCAML_TOPLEVEL_PATH', 'COLORTERM', 'XDG_CONFIG_DIRS', 'VSCODE_DEBUGPY_ADAPTER_ENDPOINTS', 'XDG_SESSION_PATH', 'HISTCONTROL', 'XDG_MENU_PREFIX', 'TERM_PROGRAM_VERSION', 'TABSIZE', 'ICEAUTHORITY', 'LANGUAGE', 'SSH_AUTH_SOCK', 'MEMORY_PRESSURE_WRITE', 'PYDEVD_DISABLE_FILE_VALIDATION', 'DESKTOP_SESSION', 'GTK_RC_FILES', 'NO_AT_BRIDGE', 'XDG_SEAT', 'PWD', 'LOGNAME', 'XDG_SESSION_DESKTOP', 'XDG_SESSION_TYPE', 'MANPATH', 'SYSTEMD_EXEC_PID', 'BUNDLED_DEBUGPY_PATH', 'XAUTHORITY', 'VSCODE_GIT_ASKPASS_NODE', 'OPAM_SWITCH_PREFIX', 'MOTD_SHOWN', 'GTK2_RC_FILES', 'HOME', 'LANG', 'XDG_CURRENT_DESKTOP', 'MEMORY_PRESSURE_WATCH', 'WAYLAND_DISPLAY', 'GIT_ASKPASS', 'XDG_SEAT_PATH', 'INVOCATION_ID', 'MANAGERPID', 'CHROME_DESKTOP', 'KDE_SESSION_UID', 'VSCODE_GIT_ASKPASS_EXTRA_ARGS', 'XKB_DEFAULT_LAYOUT', 'GEM_HOME', 'XDG_SESSION_CLASS', 'TERM', 'USER', 'VSCODE_GIT_IPC_HANDLE', 'STDPROXY_PORT', 'QT_WAYLAND_RECONNECT', 'KDE_SESSION_VERSION', 'PAM_KWALLET5_LOGIN', 'DISPLAY', 'SHLVL', 'XDG_VTNR', 'XDG_SESSION_ID', 'XDG_RUNTIME_DIR', 'DEBUGINFOD_URLS', 'VSCODE_GIT_ASKPASS_MAIN', 'JOURNAL_STREAM', 'GDK_BACKEND', 'KDE_FULL_SESSION', 'PATH', 'ORIGINAL_XDG_CURRENT_DESKTOP', 'DBUS_SESSION_BUS_ADDRESS', 'OPAMNOENVNOTICE', 'KDE_APPLICATIONS_AS_SCOPE', 'HG', 'MAIL', 'STDPROXY_CERT', 'TERM_PROGRAM', '_', , , , , , , , , , , , ]
[Voila] Connecting to: tcp://127.0.0.1:58579
[Voila] Template paths:
/usr/share/jupyter/voila/templates/lab
/usr/share/jupyter/nbconvert/templates/lab
/usr/share/jupyter/voila/templates/base
/usr/share/jupyter/nbconvert/templates/base
/home/myuser/.local/share/jupyter
/home/myuser/.local/share/jupyter/voila/templates
/home/myuser/.local/share/jupyter/nbconvert/templates
/usr/share/jupyter
/usr/share/jupyter/voila/templates
/usr/share/jupyter/nbconvert/templates
[Voila] Applying preprocessor: TagRemovePreprocessor
[Voila] Applying preprocessor: RegexRemovePreprocessor
[Voila] Applying preprocessor: HighlightMagicsPreprocessor
[Voila] Applying preprocessor: CSSHTMLHeaderPreprocessor
[Voila] Attempting to load template index.html.j2
[Voila] template_paths: /usr/share/jupyter/voila/templates/lab:/usr/share/jupyter/nbconvert/templates/lab:/usr/share/jupyter/voila/templates/base:/usr/share/jupyter/nbconvert/templates/base:/home/myuser/.local/share/jupyter:/home/myuser/.local/share/jupyter/voila/templates:/home/myuser/.local/share/jupyter/nbconvert/templates:/usr/share/jupyter:/usr/share/jupyter/voila/templates:/usr/share/jupyter/nbconvert/templates
[Voila] connecting iopub channel to tcp://127.0.0.1:58579
[Voila] Connecting to: tcp://127.0.0.1:58579
[Voila] connecting shell channel to tcp://127.0.0.1:40787
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] connecting stdin channel to tcp://127.0.0.1:55727
[Voila] Connecting to: tcp://127.0.0.1:55727
[Voila] connecting heartbeat channel to tcp://127.0.0.1:57697
[Voila] connecting control channel to tcp://127.0.0.1:37771
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Executing cell:
import ipywidgets as w
display(w.Button())
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: execute_input
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: execute_input
[Voila] msg_type: status
[Voila] content: {'execution_state': 'busy'}
[Voila] msg_type: execute_input
[Voila] content: {'code': 'import ipywidgets as w\ndisplay(w.Button())', 'execution_count': 1}
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: comm_open
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: comm_open
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: comm_open
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: display_data
[Voila] msg_type: comm_open
[Voila] content: {'data': {'state': {'_model_module': '@jupyter-widgets/base', '_model_module_version': '2.0.0', '_model_name': 'LayoutModel', '_view_count': None, '_view_module': '@jupyter-widgets/base', '_view_module_version': '2.0.0', '_view_name': 'LayoutView', 'align_content': None, 'align_items': None, 'align_self': None, 'border_bottom': None, 'border_left': None, 'border_right': None, 'border_top': None, 'bottom': None, 'display': None, 'flex': None, 'flex_flow': None, 'grid_area': None, 'grid_auto_columns': None, 'grid_auto_flow': None, 'grid_auto_rows': None, 'grid_column': None, 'grid_gap': None, 'grid_row': None, 'grid_template_areas': None, 'grid_template_columns': None, 'grid_template_rows': None, 'height': None, 'justify_content': None, 'justify_items': None, 'left': None, 'margin': None, 'max_height': None, 'max_width': None, 'min_height': None, 'min_width': None, 'object_fit': None, 'object_position': None, 'order': None, 'overflow': None, 'padding': None, 'right': None, 'top': None, 'visibility': None, 'width': None}, 'buffer_paths': []}, 'comm_id': 'eb2b5b5cae3f416183475d506b097ff4', 'target_name': 'jupyter.widget', 'target_module': None}
[Voila] msg_type: comm_open
[Voila] content: {'data': {'state': {'_model_module': '@jupyter-widgets/controls', '_model_module_version': '2.0.0', '_model_name': 'ButtonStyleModel', '_view_count': None, '_view_module': '@jupyter-widgets/base', '_view_module_version': '2.0.0', '_view_name': 'StyleView', 'button_color': None, 'font_family': None, 'font_size': None, 'font_style': None, 'font_variant': None, 'font_weight': None, 'text_color': None, 'text_decoration': None}, 'buffer_paths': []}, 'comm_id': 'c6528a29aa9f401a8ebcfc767cd990c1', 'target_name': 'jupyter.widget', 'target_module': None}
[Voila] msg_type: comm_open
[Voila] content: {'data': {'state': {'_dom_classes': [], '_model_module': '@jupyter-widgets/controls', '_model_module_version': '2.0.0', '_model_name': 'ButtonModel', '_view_count': None, '_view_module': '@jupyter-widgets/controls', '_view_module_version': '2.0.0', '_view_name': 'ButtonView', 'button_style': '', 'description': '', 'disabled': False, 'icon': '', 'layout': 'IPY_MODEL_eb2b5b5cae3f416183475d506b097ff4', 'style': 'IPY_MODEL_c6528a29aa9f401a8ebcfc767cd990c1', 'tabbable': None, 'tooltip': None}, 'buffer_paths': []}, 'comm_id': 'ab9174d345d6417c900d9b3165bf970a', 'target_name': 'jupyter.widget', 'target_module': None}
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] msg_type: display_data
[Voila] content: {'data': {'text/plain': 'Button(style=ButtonStyle())', 'application/vnd.jupyter.widget-view+json': {'version_major': 2, 'version_minor': 0, 'model_id': 'ab9174d345d6417c900d9b3165bf970a'}}, 'metadata': {}, 'transient': {}}
[Voila] msg_type: status
[Voila] content: {'execution_state': 'idle'}
[Voila] Path anywidget/static/remoteEntry.041f0a68.js served from /usr/share/jupyter/labextensions/anywidget/static/remoteEntry.041f0a68.js
[Voila] Path jupyterlab_pygments/static/remoteEntry.5cbb9d2323598fbda535.js served from /usr/share/jupyter/labextensions/jupyterlab_pygments/static/remoteEntry.5cbb9d2323598fbda535.js
[Voila] Path @voila-dashboards/widgets-manager8/static/remoteEntry.9337fdf2992b3c4e48c1.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/remoteEntry.9337fdf2992b3c4e48c1.js
[Voila] Path @voila-dashboards/widgets-manager7/static/remoteEntry.1c21df5a6606255a682b.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager7/static/remoteEntry.1c21df5a6606255a682b.js
[Voila] Path anywidget/static/387.f1b13efb.js served from /usr/share/jupyter/labextensions/anywidget/static/387.f1b13efb.js
[Voila] Path @voila-dashboards/widgets-manager8/static/651.d9c6fa52270ea21fdf9e.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/651.d9c6fa52270ea21fdf9e.js
[Voila] Path @voila-dashboards/widgets-manager8/static/264.95d855dc9ed80b79c78e.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/264.95d855dc9ed80b79c78e.js
[Voila] Path anywidget/static/807.ab4fa476.js served from /usr/share/jupyter/labextensions/anywidget/static/807.ab4fa476.js
[Voila] Path jupyterlab_pygments/static/568.1e2faa2ba0bbe59c4780.js served from /usr/share/jupyter/labextensions/jupyterlab_pygments/static/568.1e2faa2ba0bbe59c4780.js
[Voila] Path jupyterlab_pygments/static/747.67662283a5707eeb4d4c.js served from /usr/share/jupyter/labextensions/jupyterlab_pygments/static/747.67662283a5707eeb4d4c.js
[Voila] Path @voila-dashboards/widgets-manager8/static/883.74152a2e3b6d11347887.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/883.74152a2e3b6d11347887.js
[Voila] Path @voila-dashboards/widgets-manager8/static/324.2e80699c019e6df0ef30.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/324.2e80699c019e6df0ef30.js
[Voila] Path @voila-dashboards/widgets-manager8/static/603.9866b69497a4a124e57f.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/603.9866b69497a4a124e57f.js
[Voila] Path @voila-dashboards/widgets-manager8/static/496.8e7b13b84c65c7d0abf8.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager8/static/496.8e7b13b84c65c7d0abf8.js
[Voila] Path @voila-dashboards/widgets-manager7/static/122.c2a6c3e3d51be666e948.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager7/static/122.c2a6c3e3d51be666e948.js
[Voila] Path @voila-dashboards/widgets-manager7/static/496.5ad1f86424ee765927d6.js served from /usr/share/jupyter/voila/labextensions/@voila-dashboards/widgets-manager7/static/496.5ad1f86424ee765927d6.js
[Voila] Requesting kernel info from 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] Received kernel info: {'status': 'ok', 'protocol_version': '5.3', 'implementation': 'ipython', 'implementation_version': '9.4.0', 'language_info': {'name': 'python', 'version': '3.13.5', 'mimetype': 'text/x-python', 'codemirror_mode': {'name': 'ipython', 'version': 3}, 'pygments_lexer': 'ipython3', 'nbconvert_exporter': 'python', 'file_extension': '.py'}, 'banner': "Python 3.13.5 (main, Jun 21 2025, 09:35:00) [GCC 15.1.1 20250425]\nType 'copyright', 'credits' or 'license' for more information\nIPython 9.4.0 -- An enhanced Interactive Python. Type '?' for help.\nTip: Put a ';' at the end of a line to suppress the printing of output.\n", 'help_links': [{'text': 'Python Reference', 'url': 'https://docs.python.org/3.13'}, {'text': 'IPython Reference', 'url': 'https://ipython.org/documentation.html'}, {'text': 'NumPy Reference', 'url': 'https://docs.scipy.org/doc/numpy/reference/'}, {'text': 'SciPy Reference', 'url': 'https://docs.scipy.org/doc/scipy/reference/'}, {'text': 'Matplotlib Reference', 'url': 'https://matplotlib.org/contents.html'}, {'text': 'SymPy Reference', 'url': 'http://docs.sympy.org/latest/index.html'}, {'text': 'pandas Reference', 'url': 'https://pandas.pydata.org/pandas-docs/stable/'}]}
[Voila] Opening websocket /api/kernels/63762c06-5ddf-4849-856b-f8529d6926de/channels
[Voila] Connecting to kernel 63762c06-5ddf-4849-856b-f8529d6926de.
[Voila] Getting buffer for 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Connecting to: tcp://127.0.0.1:58579
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Connecting to: tcp://127.0.0.1:55727
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Nudge: attempt 1 on kernel 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: IOPub received: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: resolving iopub future: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] Nudge: control info reply received: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: resolving control future: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] Opening websocket /api/kernels/63762c06-5ddf-4849-856b-f8529d6926de/channels
[Voila] Connecting to kernel 63762c06-5ddf-4849-856b-f8529d6926de.
[Voila] Getting buffer for 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Connecting to: tcp://127.0.0.1:58579
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Connecting to: tcp://127.0.0.1:55727
[Voila] Connecting to: tcp://127.0.0.1:40787
[Voila] Connecting to: tcp://127.0.0.1:37771
[Voila] Nudge: attempt 1 on kernel 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: IOPub received: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: resolving iopub future: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] Nudge: shell info reply received: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] Nudge: resolving shell future: 63762c06-5ddf-4849-856b-f8529d6926de
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: comm_msg
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: comm_msg
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (busy)
[Voila] activity on 63762c06-5ddf-4849-856b-f8529d6926de: status (idle)
Originally posted by @ThePirate42 in #1472