NUVOLOS
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  • Getting Started
    • Introduction to Nuvolos
    • Documentation structure
    • Nuvolos basic concepts
      • Organisational hierarchy
      • Applications
      • Distribution
      • Data integration
      • Snapshots
      • Background tasks
    • Navigate in Nuvolos
    • Quickstart tutorials
      • Research
      • Education (instructor)
      • Education (student)
  • Features
    • Applications
      • Application resources
      • Sessions
        • Session Logs
      • Install a software package
      • Create a persistent .bashrc
      • Automatic code execution
      • Long-running applications
      • Troubleshooting applications
      • New applications or licenses
      • Configuring applications
      • Exporting applications
      • Add-ons
        • MariaDB add-on
        • PostgreSQL add-on
        • OpenSearch add-on
        • MongoDB add-on
        • Redis add-on
        • PostGIS add-on
        • Rclone mount add-on
        • Neo4j add-on
    • File system and storage
      • File navigator
      • Large File Storage
      • Preview files
      • Mount Dropbox
      • Access S3 buckets with RClone
      • Access remote files with SSHFS
      • Access files on SharePoint Online
    • Object distribution
      • Distribution strategies
      • The distributed instance
    • Snapshots
      • Create a snapshot
      • Restore a snapshot
      • Delete a snapshot
    • Database integration
      • Create datasets
      • View tables
      • Build queries
      • Upload data
      • Access data from applications
        • Set up ODBC drivers
        • Obtain tokens for data access
        • Find database and schema path
      • DBeaver integration
    • Environment variables and secrets
    • Searching
      • Page
      • Find an application
      • Find an organisation
      • Find a space
      • Find an instance
      • Find a state
    • Video library
    • Nuvolos CLI and Python API
      • Installing the CLI
      • Using the CLI
  • User Guides
    • Research guides
      • Inviting a reviewer
      • GPU computation
    • Education guides
      • Setting assignments
        • Programmatical assignment handling
      • Documenting your course
      • Setting up group projects
        • Collaborative application editing
      • Configuring student applications
      • Archiving your course
      • Student guides
        • Joining a course
        • Working on assignments
        • Leaving a course
    • Application-specific guides
      • JupyterLab
      • RStudio
      • VSCode
      • Stata
      • MATLAB
      • Terminal
      • Terminal [tmux]
      • Apache Airflow
      • Apache Superset
      • D-Wave Inspector
      • MLFlow
      • Databricks Connect
      • Dynare.jl
      • CloudBeaver
      • InveLab
      • Overleaf
      • Metabase
      • DNDCv.CAN
      • OpenMetaData
      • Uploading data to the Large File Storage
    • Data guides
      • Setting up a dataset on Nuvolos
      • Importing data on Nuvolos
      • A complete database research workflow (Matlab & RStudio)
      • Accessing data as data.frames in R
      • Working with CRSP and Compustat
      • Working with the S&P 500®
  • Pricing and Billing
    • Pricing structure
    • Resource pools and budgets
    • Nuvolos Compute Units (NCUs)
  • Administration
    • Roles
      • Requesting roles
    • Organisation management
    • Space management
      • Invite to a space
      • Revoke a space user
      • HPC spaces
      • Resting spaces
    • Instance management
      • Invite to an instance
    • Enabling extra services
    • Monitoring resource usage
      • NCU Limits and Capacities
  • Reference
    • Application reference
      • InveLab
        • Dataset selection
        • Modules
          • Time-series visualisation
          • Moment estimation
          • Mean-variance frontiers
          • Frontiers
          • Dynamic strategy
          • Portfolio analysis
          • Performance analysis
          • Benchmarking
          • Carry trade strategies
          • Risk measures
          • Conditional volatility
          • Replication
          • Factor factory
          • Factor tilting
          • Valuation
    • Glossary
  • FAQs
    • FAQs
    • Troubleshooting
      • Login troubleshooting
        • I forgot my email address
        • I forgot my identity provider
        • I can't log in to Nuvolos
        • I forgot my password
        • I haven't received the password reset email
        • I haven't received the invitation email
      • Application troubleshooting
        • I can't see an application
        • I can't start an application
        • I can't create an application
        • I can't delete an application
        • I can't stop a running application
        • JupyterLab 3 troubleshooting
        • Spyder 3.7 troubleshooting
      • Administration troubleshooting
        • I can't see a space
        • I can't create a space
        • I can't delete a space
        • I can't invite admins to my space
        • I can't see an instance
        • I can't create an instance
        • I can't delete an instance
        • I can't invite users to an instance
        • I can't see distributed content in my instance
        • I can't see a snapshot
        • I can't create a snapshot
        • I can't delete a snapshot
        • I can't revoke a user role
        • I can't upload a file
        • I can't delete a file
        • I can't invite students to my course
      • Content troubleshooting
        • I can't find my files in my Linux home
        • I can't find my files among the Workspace files
        • I restored a snapshot by mistake
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On this page
  • File save error
  • Running a Flask application and serving it to JupyterLab
  • Modify your flask application code

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  1. FAQs
  2. Troubleshooting
  3. Application troubleshooting

JupyterLab 3 troubleshooting

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Last updated 8 months ago

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File save error

In rare occasions, one of the many database files used internally by JupyterLab can get corrupted, preventing the save of any changes to documents. You might see something like this on the UI:

If you encounter this, try the following steps:

  1. Open new terminal window, and execute jupyter lab path. You'll see something like Application directory: /opt/conda/share/jupyter/lab

  2. Take the directory path, and issue the following command rm <app_dir_path>/../nbsignatures.db example: rm /opt/conda/share/jupyter/lab/../nbsignatures.db

  3. Restart the application

Running a Flask application and serving it to JupyterLab

You are able to run a Flask webserver application and make it visible in JupyterLab.

Components you need:

  • Install nodejs from conda

    • nodejs is needed for commands such as jupyter labextension install and jupyter lab build. You might need to install a specific version of nodejs depending on the JupyterLab version. Currently version >=12.0.0 is required.

  • Flask version >= 2.2.0 is suggested.

Potential further useful tools:

Modify your flask application code

Make sure you add the following snippet to your flask application code:

from werkzeug.middleware.proxy_fix import ProxyFix
from werkzeug.middleware.dispatcher import DispatcherMiddleware
from werkzeug.wrappers import Response

# ...
# your code goes here
# ...


app.wsgi_app = DispatcherMiddleware(
     Response('Not Found', status=404),
     {'/proxy/absolute/5000': ProxyFix(app.wsgi_app)})

Install the extension.

We suggest also looking at the extension.

jupyter-server-proxy
jupyterlab_iframe
File save error: database disk image is malformed