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EADDRINUSE error: Sanity Studio won't start, port 3333 already in use

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Last updated: Nov 29, 2025
Got this error and studio won't start up at all.. have no idea where it can come from either:
sanity-gatsby-blog-studio: events.js:174
sanity-gatsby-blog-studio:       throw er; // Unhandled 'error' event
sanity-gatsby-blog-studio:       ^
sanity-gatsby-blog-studio: Error: listen EADDRINUSE: address already in use 127.0.0.1:3333
sanity-gatsby-blog-studio:     at Server.setupListenHandle [as _listen2] (net.js:1279:14)
sanity-gatsby-blog-studio:     at listenInCluster (net.js:1327:12)
sanity-gatsby-blog-studio:     at GetAddrInfoReqWrap.doListen [as callback] (net.js:1460:7)
sanity-gatsby-blog-studio:     at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:61:10)
sanity-gatsby-blog-studio: Emitted 'error' event at:
sanity-gatsby-blog-studio:     at emitErrorNT (net.js:1306:8)
sanity-gatsby-blog-studio:     at process._tickCallback (internal/process/next_tick.js:63:19)
sanity-gatsby-blog-studio: npm ERR! code ELIFECYCLE
sanity-gatsby-blog-studio: npm ERR! errno 1
sanity-gatsby-blog-studio: npm ERR! sanity-gatsby-blog-studio@1.0.13 dev: `sanity start`
sanity-gatsby-blog-studio: npm ERR! Exit status 1
sanity-gatsby-blog-studio: npm ERR! 
sanity-gatsby-blog-studio: npm ERR! Failed at the sanity-gatsby-blog-studio@1.0.13 dev script.
sanity-gatsby-blog-studio: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
sanity-gatsby-blog-studio: npm ERR! A complete log of this run can be found in:
AI Update

This is a classic port conflict error - the EADDRINUSE: address already in use 127.0.0.1:3333 message means something is already running on port 3333, which is where Sanity Studio is trying to start.

Here are a few ways to fix this:

1. Find and kill the process using port 3333:

On Mac/Linux:

lsof -ti:3333 | xargs kill -9

Or find the process ID first to see what it is:

lsof -i:3333

On Windows (Command Prompt):

netstat -ano | findstr :3333
taskkill /PID <PID_NUMBER> /F

2. Use a different port:

You can start Sanity Studio on a different port by adding the --port flag:

sanity start --port 3334

3. Common causes:

  • You might have another Sanity Studio instance already running in a different terminal/tab
  • Your Gatsby dev server might be using that port
  • A previous Studio process didn't shut down cleanly
  • You have another development server configured to use port 3333

4. Nuclear option - restart your terminal/computer:

If you can't find the process, sometimes the easiest solution is to close all terminal windows and restart, or restart your computer entirely.

The most likely scenario is that you have another instance of sanity start already running somewhere. Check all your terminal windows/tabs first before killing processes!

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