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SDSU Research & Cyberinfrastructure

Fixing Connection Refused

Have you encountered an error message like this and are unable to get to VERNE?

Connection refused

Sometimes a network error may occur while accessing our JupyterHub instance, so here a few things to try to troubleshoot the issue.

Try another Browser

If time is of the essence, try opening https://jupyterhub.sdsu.edu/ in a different browser, if you have another browser installed already.

Open In Private or Icognito Tab

If you don’t have a second browser available, or are attached to a specific browser, then you can try opening a private or igcognito tab.

Flush DNS Cache - Advanced

If the above options didn’t work for you, then you can try to flush your browser’s DNS (Domain Name Service) cache.

  • Note: This will increase your page load times to sites, thus why this is a last resort.
  1. Open a new tab
  2. Copy and paste the page URL for your browser’s DNS settings page
    • Browser Page URL
      Chrome chrome://net-internals/#dns
      Edge edge://net-internals/#dns
      Firefox about:networking#dns
  3. Search the page for a button along the lines of “Clear Cache”
    • Clear Cache
  4. Click the button
  5. Close and re-open your browser
  6. Try signing in again at https://jupyterhub.sdsu.edu/

If that doesn’t work, then please let your instructor know and ask them to report the issue to Research and Cyberinfrastructure.