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Tabnine "Failed to connect" Error (Cannot Connect to API)

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Ongoing macOS, Linux, Windows (Tabnine CLI) Updated November 14, 2026Based on 2 user reportsHow we research

Quick answer

Tabnine CLI shows "Failed to connect" when it cannot reach api.tabnine.com. Usually a blocked port 443, a firewall or missing proxy settings.

Most likely fix: Check connectivity and the firewall

How to fix it

Try these in order — the most common fix is first.

  1. 1. Check connectivity and the firewall

    1. Run: ping api.tabnine.com
    2. Confirm outbound port 443 is allowed by your firewall
    Did this fix it?

  2. 2. Set proxy variables

    1. export NODE_USE_ENV_PROXY=1
    2. export HTTP_PROXY=http://proxy:8080 and export HTTPS_PROXY=http://proxy:8080
    3. Start the CLI again with: tabnine
    Did this fix it?

  3. 3. Run in debug mode

    1. Run: DEBUG=1 tabnine
    2. Or inside the CLI: /debug on
    Did this fix it?

Symptoms

The CLI prints "Failed to connect" or "Failed to connect to Tabnine API" and no response arrives.

Why it happens

  • No network route to api.tabnine.com
  • Port 443 blocked by a firewall
  • Proxy environment variables not set

This guide also covers

  • tabnine failed to connect
  • tabnine cannot connect to api
  • tabnine not working firewall

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